Hindawi Publishing CorporationInternational Journal of Antennas and PropagationVolume 2013 Article ID 270845 7 pageshttpdxdoiorg1011552013270845
Research ArticleA Modified Vivaldi Antenna for Improved Angular-DependentFidelity Property
Zhi Zeng1 Ke Xu2 Zhaohui Song3 and Qinyu Zhang1
1 Shenzhen Graduate School Harbin Institute of Technology Shenzhen 518055 China2 Graduate School Harbin Institute of Technology Harbin 150001 China3Harbin Institute of Technology Harbin 150001 China
Correspondence should be addressed to Qinyu Zhang zqyhiteducn
Received 23 December 2012 Revised 10 April 2013 Accepted 4 May 2013
Academic Editor Renato Cicchetti
Copyright copy 2013 Zhi Zeng et alThis is an open access article distributed under the Creative CommonsAttribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited
The analysis design and realization of a modified Vivaldi antenna optimized for time domain fidelity factor in the half-spacelocated in the direction of the antennamain beam are presentedThe proposed antenna shows improved angular-dependent fidelityproperty with respect to the signal transmitted in the main beam direction A substantial increase in the fidelity factor is achievedby utilizing spatial filter effect introduced by adding two dielectric slabs parallel to the antenna substrate By choosing optimaldimensions and location of the slabs the signal waveforms in thementioned half-space are equalized so as to improve the quality ofthe radiated signal waveform in the main beam direction As a result the fidelity property in the half-space is improved greatlyThesimulated andmeasured fidelity factor in the angular operational region is studied and comparedwith experimentalmeasurementsThe ranges with the fidelity factor better than the value of 09 are improved by 95 in H-plane and by 14 in E-plane respectively
1 Introduction
Since Federal Communication Commission (FCC) of USAopened up the frequency range 31ndash106GHz for ultrawide-band (UWB) communication in 2002 UWB has attracteda lot of attention in the wireless communications field fromboth academia and industries [1] UWB system has manyadvantages such as high data rate high spatial resolutionlow-cost transceiver low transmit power and low inter-ference which are quite suited to short-range high-ratecommunication real-time localization and see-through-the-wall and ground penetrating radar [2 3] There have beenlots of investigations about these UWB applications some ofthem have already been commercially used
UWB antenna is one of the key parts in UWB system Awell-designed UWB antenna should have a wide bandwidtha stable gain pattern that ensures a flat magnitude of thetransfer function and a linear phase response characteristicsuseful to minimize the distortion of the transmittedreceivedpulses [4] In [5] a nondirective UWB printed antenna forwireless applications characterized by a low group delay
excellent integration capability with the activepassive com-ponents forming the receivertransmitter front end and goodradiative performances when arranged in arrays has beenpresented In [6] an UWB antenna that rejects extremelysharply the two narrow and closely spaced USWLAN 80211abands is presented while in [7] a compact low dispersiveUWB antenna with sectorial radiation pattern and high frontto back ratio has been proposed
Vivaldi antenna is a kind of tapered slot UWB antennaThe first tapered slot antenna was presented by Lewis et alin 1974 [8] and named Vivaldi antenna by Gibson in 1979[9] Vivaldi antennas are widely used in UWB system forits wide bandwidth high directivity low cross-polarizationand easy fabrication During the past decades many inves-tigators studied Vivaldi antennas The miniaturization andthe bandwidth performances are key requirements in thedesign of modern wideband antennas In this context Hoodpresented a compact Vivaldi antenna fabricated with a394times 346mm substrate which operates in the frequencyband 33ndash106GHz [10] In [11] a slot loaded Vivaldi antennawith bandwidth over 25 1 is presented In addition the pulse
2 International Journal of Antennas and Propagation
W
L
x
z
0
119862119886
1198711
1198771
(a)
0
z
x
119882119891120572
1198712
1198772
(b)
W
L
x
z
0
119862119886
1198711
1198771
(c)
Figure 1 Geometry of the original Vivaldi antenna (a) top view (b)central layer (feed) and (c) bottom view
120593
120579
x
y
z
Antenna0
Figure 2 Vivaldi antenna (the reference frame is indicated in thefigure)
radiation characteristics are quite important for antennasused in the impulse UWB system In [12] the authors studiedthe transient distortion reflection coefficient and cross-polarization level of Vivaldi antenna Vivaldi antenna is quitefitting for UWB antenna array due to its wide bandwidthhigh directivity low cross-polarization and low profileIn the past decades especially after the computer is gettingpowerful enough to analyze antenna arrays many inves-tigations were carried out to improve the performance ofVivaldi antenna arrays As of this time no competing arraytechnology canmatch thewide bandwidth andwide scanning
0 05 1
minus1
minus05
0
05
1
Sign
al st
reng
th (V
)
Time (ns)
Figure 3 Excitation signal
375 4 425 45 475
minus05
0
05
1
Time (ns)
120579 = 0120579 = 30
120579 = 60120579 = 90
minus1
Figure 4 Normalized radiation signal waveform in E-plane (120593 =0∘)
375 4 425 45 475
minus05
0
05
1
Time (ns)
120579 = 0120579 = 30
120579 = 60120579 = 90
minus1
Figure 5 Normalized radiation signal waveform in H-plane (120593 =90∘)
International Journal of Antennas and Propagation 3
impedance performance of Vivaldi antenna arrays which arewidely used in modern electronic warfare system and radarsystem [13 14]
It is quite important for an antenna array element tokeep good performance in a wide spatial region whilethe main beam is scanning In practice all the antennasradiate different signals in different spatial directions Soit is quite important to study the correlation between thesignal radiated and spatial directions both in frequencyand in time domains In [15] the angular distortion of thesignal radiated with respect to that emitted in the mainbeam direction of UWB antennas has been investigated Thecorrelation properties of the pulse signals are determinedby the so-called fidelity factor It can be quantified throughthe analysis of the correlation between the signal in anarbitrary angular direction and the signal in the main beamdirection Usually a fidelity factor which is greater than thevalue of 09 could be considered to be acceptable In [16]Quintero et al introduced system fidelity factor (SFF) tocompare UWB antennas In [3] the half-spherical fidelityfactor pattern measurement results of Bowtie and Vivaldiantenna are presented The fidelity factor pattern describeshow does the signal vary in the different angular directionswith respect to the signal in the main beam direction In [17]Pancera and Wiesbeck introduced an optimization methodbased on the fidelity factor criterion to improve the radiationproperties of Bowtie antennas for medical applications
In this paper a method to improve the fidelity factor ofVivaldi antenna in spatial range is presented The originalVivaldi antenna operates in the frequency band 31ndash106GHzThemodified antenna has two dielectric slabs that are parallelto the antenna substrate These dielectric slabs are located ata distance 119889 from the upper and bottom faces of the antennaThe dielectric slabs act as a spatial filter to reform the signalwaveform Using the GA algorithm the parameters of thedielectric slabs have been optimized producing an incrementof the fidelity factor in a larger angular range The simu-lations of both original antenna and improved antenna areperformed using the commercial electromagnetic simulationsoftware CST MWS The available ranges with the fidelityfactor greater than the value of 09 in H-plane and in E-planeare improved by 95 and 14 respectivelyThe prototypes ofboth original antenna and improved antenna were fabricatedandmeasuredThe numerical results concerning the antennaparameters are found to be in good agreement with theexperimental measurements
2 Improvement of the Vivaldi AntennaFidelity Factor
21 Original Vivaldi Antenna Vivaldi antenna is one kindof classic end-fired directive travelling wave antennas whichhas a tapered slot characterized by a bell-shaped exponentialon it The slot curve on the substrate board becomes widergradually from the narrow end to thewide end and it radiatesthe electromagnetic waves using the corresponding part ofthe slot as constant electric size at the relevant frequency Sotheoretically Vivaldi antenna has an infinite wide frequency
Ws
x
y
0
Dielectric slab
119882119904
1198713
119871119904
(a)
0
y
x
d
t
Ant
enna
Die
lect
ric sl
ab(b)
Figure 6 Geometry of the improved Vivaldi antenna (a) top viewand (b) lateral view
band [5] In practice Vivaldi antenna has a band width betterthan 10 1 and has the features of low cross-polarization andhighly directive radiation patterns over the whole frequencyband In this paper a Vivaldi antenna operating in thefrequency band 31ndash106GHz is investigated The antenna isfabricated on a two-layer substrate with dielectric constantof 35 size of 85mmlowast70mm and each layer thickness of08mm The geometry of the original Vivaldi antenna isshown in Figure 1 with the xz-plane and yz-plane referred toas the E-plane and H-plane respectivelyThe reference frameadopted to express the field quantities is shown in Figure 2The tapers of the antennas are defined as
119909 = plusmn 119888119886sdot exp [119888
119887(119910 minus 10)] (1)
The values of the antenna geometrical parameters are shownin Table 1
A commercial Finite IntegrationTechnique (FIT) electro-magnetic simulation software CST MWS is used to analyzethe radiative performances of the Vivaldi antenna Theantenna is excited by aUWB signal in the frequency band 31ndash106GHz which is a Gaussian pulse in the frequency band 0ndash375GHzmodulated by a cosine wave carrier at the frequency
4 International Journal of Antennas and Propagation
minus90 minus70 minus50 minus30 3010minus10 50 70 900
010203040506070809
1
Improved antennaOriginal antenna
Fide
lity
fact
or in
H-p
lane
120579 (deg)
(a)
0010203040506070809
1
Fide
lity
fact
or in
E-p
lane
120579 (deg)
Improved antennaOriginal antenna
minus90 minus70 minus50 minus30 3010minus10 50 70 90
(b)
Figure 7 (a) Simulation results of fidelity factor in H-plane (120593 =90∘) and (b) simulation results of fidelity factor in E-plane (120593 = 0∘)
685GHz The waveform of excitation signal is shown inFigure 3 A set of probes have been placed at a distance of1000mm from the antenna on a plane around the antennaand spaced by 5 degrees to detect the time-domain signalradiated by the antenna Since the Vivaldi antenna has quitegood cross-polar property only the copolar radiation signalsare consideredThe normalized signal waveforms at themainbeam direction and other directions computed in the E- andH-planes are shown in Figures 4 and 5 respectively
The fidelity factor between the signal at the main beamdirection 119878
1(119905) and the signal in an arbitrary angular direction
1198782(119905) is defined as the normalized cross-correlation between
them and can be calculated by [3]
fidelity = max120591
int
+infin
minusinfin
1198781(119905 minus 120591) 119878
2(119905) 119889119905
radicint
+infin
minusinfin
10038171003817100381710038171198781(119905)1003817100381710038171003817
2
119889119905 int
+infin
minusinfin
10038171003817100381710038171198781(119905)1003817100381710038171003817
2
119889119905
(2)
(a)
(b)
Figure 8 (a) Picture of the original antenna and (b) picture of theimproved antenna
0 1 2 3 4 5 6 7 8 9 10 11 12 13minus40
minus35
minus30
minus25
minus20
minus15
minus10
minus5
0
MeasurementSimulation
|11987811|
(dB)
Frequency (GHz)
Figure 9 |11987811
| of improved antenna
The fidelity factor results computed in E- and H-planes arelisted in Table 2
From Table 2 it appears that the fidelity factor in H-planedegrades quickly as the angle between the antennarsquos mainbeam and the observation point is larger than 35 degrees
International Journal of Antennas and Propagation 5
Table 1 Geometrical parameters of the original Vivaldi antenna
Parameter Value Unit119882 70 mm119871 85 mm1198711
10 mm1198712
1225 mm119882119891
085 mm1198771
207 mm1198772
33 mm120572 46 ∘
119862119886
04440119862119887
00559
Table 2 Computed fidelity factor of the original antenna inH-planeand E-plane
H-plane (120593 = 90) E-plane (120593 = 0)120579 (degree) Fidelity factor 120579 (degree) Fidelity factor0 1 0 15 099998 5 09918210 099157 10 09915415 099012 15 09904020 098533 20 09875825 097260 25 09826330 094303 30 09762635 088816 35 09732040 077987 40 09700445 062700 45 09731850 046141 50 09755855 053453 55 09728860 053101 60 09615465 044638 65 09322670 034619 70 08661575 033003 75 07383080 035294 80 05776685 035444 85 063184
And this distortion will cause poor performance degradationwhile the beam is scanning out of this range
To improve the signal fidelity factor in a larger angularregion two dielectric slabs with relative dielectric constant120576119903and thickness 119905 which parallel the antenna substrate are
added to the original Vivaldi antenna The distance betweenthe slabs and antenna substrate is 119889 The structure of theproposed antenna is shown in Figure 6
The dielectric slabs play a role as a spatial filter whichhave the angular-dependant effect on the incident wave Soby proper tuning of 120576
119903 119905 and 119889 the quality of the radiated
wave can be restored This effect can be used to optimizethe antenna fidelity factor in the angular operational regionBesides the parameters above the length of the slabs 119871
119904and
the position of the slabs along the 119910-axis 1198713also can be
considered as optimization parameters because they decidethe angular range covered by the slabs
minus80 minus60 minus40 minus20 0 20 40 60 80
minus80
minus60
minus40
minus20
0
20
40
60
80
Azimuth angle (deg)
Elev
atio
n an
gle (
deg)
05
06
07
08
09
092
094
096
098
(a)
05
06
07
08
09
092
094
096
098
minus80 minus60 minus40 minus20 0 20 40 60 80
minus80
minus60
minus40
minus20
0
20
40
60
80
Azimuth (deg)
Elev
atio
n (d
eg)
(b)
Figure 10 (a) Fidelity factor test results of the original antenna and(b) fidelity factor test results of the improved antenna
3 Antenna Simulation and Measurement
The polyformaldehyde having a relative dielectric constant120576119903= 38 is chosen for the realization of the two dielectric
slabs thanks to its intrinsic characteristics consisting in theeasy machining and good temperature characteristics Thestructure of the Vivaldi antenna is optimized with the goalof the better fidelity factor in H-plane and in E-plane usingGenetic Algorithms optimizer in CSTMWSThe criterion ofthe fidelity factor is set to 09 The optimal parameters of thedielectric slabs are listed in Table 3
The fidelity factor of improved antenna computed in E-plane and H-plane is listed in Table 4 and compared with theresults of the original antenna as shown in Figure 7
The fidelity factor in H-plane has been improved signifi-cantly The available range of the original antenna in H-planeis 70 degrees and the improved antenna has an availablerange wider than 135 degrees which has been improved byabout 97 Besides that the available range in E-plane hasbeen improved from 136 degrees to 156 degrees which is notsuch remarkable as that in H-plane
6 International Journal of Antennas and Propagation
0010203040506070809
1
Improved antennaOriginal antenna
Fide
lity
fact
or in
H-p
lane
minus90 minus70 minus50 minus30 3010minus10 50 70 90120579 (deg)
(a)
0
010203040506070809
1
Fide
lity
fact
or in
E-p
lane
120579 (deg)
Improved antennaOriginal antenna
minus90 minus70 minus50 minus30 3010minus10 50 70 90
(b)
Figure 11 (a) Measurement results of fidelity factor in H-plane and(b) measurement results of fidelity factor in E-plane
Table 3 The geometrical parameters of the dielectric slabs
Parameter Value Unit119905 44 mm119882119904
40 mm1198713
43 mm119889 915 mm119871119904
70 mm
The prototypes of the two considered antennas are shownin Figure 8 while the numerical and measurement resultsconcerning the frequency behavior of the parameter |119878
11| of
the new antenna are reported in Figure 9The measurement of fidelity factor was carried out in
an enclosed anechoic chamber The measured antenna isinstalled on a rotating platform A wideband probe is used
Table 4 Fidelity factor of the improved antenna computed in E-plane and H-plane
H-plane (120593 = 90) E-plane (120593 = 0)120579 (degree) Fidelity factor 120579 (degree) Fidelity factor0 1 0 15 099995 5 09999510 098976 10 09997315 098881 15 09988820 098655 20 09970925 098285 25 09942130 097808 30 09902335 097300 35 09852140 097008 40 09790745 096478 45 09718650 095924 50 09650455 095839 55 09613760 095966 60 09624465 093783 65 09656670 086216 70 09615675 071946 75 09335180 049866 80 08640485 027054 85 074927
to receive the transient signal radiated by the antenna undertest when changing the azimuth and the elevation angle ofthe antennaThe fidelity factors calculated in the upper half-plane are plotted in Figure 10Themeasurement results of thefidelity factor in E-plane and H-plane are shown in Figure 11
The original Vivaldi antenna shows its good fidelity factorcharacteristics in a side-ways H-shape area with azimuthangle scanning less than 35 degrees in H-plane and elevationangle less than 65 degrees in E-plane respectively Theimproved Vivaldi antenna shows its good fidelity factorcharacteristics in a cross-shape area with azimuth anglescanning better than 65 degrees in H-plane and elevationangle better than 70 degrees in E-plane respectively whichis extended in horizontal direction significantly
4 Conclusion
In this paper a new method to improve the fidelity factorof a planar Vivaldi UWB antenna has been proposed Twodielectric slabs which play the role of a spatial filter suitableto restore the signal waveform in time domain are added tothe original Vivaldi antenna By tuning the dimensions andthe relative position of the dielectric slabs the fidelity factorin the half space is optimized The angular available range inH-plane with the fidelity factor greater than the value of 09has been improved by 95 and the available angular range inE-plane has been improved by 14
Acknowledgments
The authors would like to express their sincere gratitude toCSTLtd Germany for providing a free package of CSTMWS
International Journal of Antennas and Propagation 7
softwareThis workwas supported in part by the key programof the National Natural Science Foundation of China underGrant 61032003 and the National Basic Research Program ofChina under Grant 2009CB320402
References
[1] Y Q Zhang Y X Guo and M S Leong ldquoA novel multilayerUWB antenna on LTCCrdquo IEEE Transactions on Antennas andPropagation vol 58 no 9 pp 3013ndash3019 2010
[2] T A Vu M Z Dooghabadi S Sudalaiyandi et al ldquoUWBVivaldi antenna for impulse radio beamformingrdquo inProceedingsof the 27th Norchip Conference pp 1ndash5 Trondeim NorwayNovember 2009
[3] E Pancera T Zwick and W Wiesbeck ldquoSpherical fidelitypatterns of UWB antennasrdquo IEEE Transactions on Antennas andPropagation vol 59 no 6 pp 2111ndash2119 2011
[4] F Gross Frontiers in Antennas Next Generation Design ampEngineering McGraw-Hill 2011
[5] G Cappelletti D Caratelli R Cicchetti and M SimeonildquoA low profile printed drop-shaped dipole antenna for wide-band wireless applicationsrdquo IEEE Transactions on Antennas andPropagation vol 59 no 10 pp 3526ndash3535 2011
[6] A A Gheethan and D E Anagnostou ldquoDual band-reject UWBantenna with sharp rejection of narrow and closely-spacedbandsrdquo IEEETransactions onAntennas and Propagation vol 60no 4 pp 2071ndash2076 2012
[7] L Desrumaux A Godard M Lalande V Bertrand J Andrieuand B Jecko ldquoAn original antenna for transient high powerUWB arrays the Shark antennardquo IEEE Transactions on Anten-nas and Propagation vol 58 no 8 pp 2515ndash2522 2010
[8] L R LewisM Fassett and J Hunt ldquoA broadband stripline arrayelementrdquo in Proceedings of the IEEE Antennas and PropagationSymposium Digest pp 335ndash337 Atlanta Ga USA 1974
[9] Y Li and A Chen ldquoDesign and application of Vivaldi antennaarrayrdquo in Proceedings of the 8th International Symposium onAntennas Propagation andEMTheory (ISAPE rsquo08) pp 267ndash270Kunming China November 2008
[10] A Z Hood T Karacolak and E Topsakal ldquoA small antipodalvivaldi antenna for ultrawide-band applicationsrdquo IEEE Anten-nas and Wireless Propagation Letters vol 7 pp 656ndash660 2008
[11] J Bai S Shi and D W Prather ldquoUltra-wideband slot-loaded antipodal Vivaldi antenna arrayrdquo in Proceedings of theIEEE International Symposium on Antennas and Propagation(APSURSI rsquo11) pp 79ndash81 Spokane Wash USA 2011
[12] J Zhang J Wang and W Hu ldquoAnalysis of UWB signal distor-tion in transmittingreceiving antenna systemsrdquo in Proceedingsof the 9th International Symposium on Antennas Propagationand EM Theory (ISAPE rsquo10) pp 163ndash166 Guangzhou ChinaDecember 2010
[13] K Trott B Cummings R Cavener M Deluca J Biondi andT Sikina ldquoWideband phased array radiatorrdquo in Proceedings ofthe IEEE International Symposium on Phased Array Systems ampTechnology pp 383ndash386 Boston Mass USA October 2003
[14] D Carsenat and C Decroze ldquoUWB antennas beamformingusing passive time-reversal devicerdquo IEEE Antennas andWirelessPropagation Letters vol 11 pp 779ndash782 2012
[15] M A Elmansouri andD S Filipovic ldquoPulse distortion andmit-igation thereof in spiral antenna-based UWB communicationsystemsrdquo IEEE Antennas and Wireless Propagation Letters vol59 no 10 pp 3863ndash3871 2011
[16] G Quintero J F Zurcher and A K Skrivervik ldquoSystem fidelityfactor a new method for comparing UWB antennasrdquo IEEETransactions on Antennas and Propagation vol 59 no 7 pp2502ndash2512 2011
[17] E Pancera and W Wiesbeck ldquoFidelity based optimization ofUWB antenna-radiation for medical applicationsrdquo in Proceed-ings of the IEEE International Symposium on Antennas andPropagation (APSURSI rsquo11) p 2411 Spokane Wash USA July2011
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of
2 International Journal of Antennas and Propagation
W
L
x
z
0
119862119886
1198711
1198771
(a)
0
z
x
119882119891120572
1198712
1198772
(b)
W
L
x
z
0
119862119886
1198711
1198771
(c)
Figure 1 Geometry of the original Vivaldi antenna (a) top view (b)central layer (feed) and (c) bottom view
120593
120579
x
y
z
Antenna0
Figure 2 Vivaldi antenna (the reference frame is indicated in thefigure)
radiation characteristics are quite important for antennasused in the impulse UWB system In [12] the authors studiedthe transient distortion reflection coefficient and cross-polarization level of Vivaldi antenna Vivaldi antenna is quitefitting for UWB antenna array due to its wide bandwidthhigh directivity low cross-polarization and low profileIn the past decades especially after the computer is gettingpowerful enough to analyze antenna arrays many inves-tigations were carried out to improve the performance ofVivaldi antenna arrays As of this time no competing arraytechnology canmatch thewide bandwidth andwide scanning
0 05 1
minus1
minus05
0
05
1
Sign
al st
reng
th (V
)
Time (ns)
Figure 3 Excitation signal
375 4 425 45 475
minus05
0
05
1
Time (ns)
120579 = 0120579 = 30
120579 = 60120579 = 90
minus1
Figure 4 Normalized radiation signal waveform in E-plane (120593 =0∘)
375 4 425 45 475
minus05
0
05
1
Time (ns)
120579 = 0120579 = 30
120579 = 60120579 = 90
minus1
Figure 5 Normalized radiation signal waveform in H-plane (120593 =90∘)
International Journal of Antennas and Propagation 3
impedance performance of Vivaldi antenna arrays which arewidely used in modern electronic warfare system and radarsystem [13 14]
It is quite important for an antenna array element tokeep good performance in a wide spatial region whilethe main beam is scanning In practice all the antennasradiate different signals in different spatial directions Soit is quite important to study the correlation between thesignal radiated and spatial directions both in frequencyand in time domains In [15] the angular distortion of thesignal radiated with respect to that emitted in the mainbeam direction of UWB antennas has been investigated Thecorrelation properties of the pulse signals are determinedby the so-called fidelity factor It can be quantified throughthe analysis of the correlation between the signal in anarbitrary angular direction and the signal in the main beamdirection Usually a fidelity factor which is greater than thevalue of 09 could be considered to be acceptable In [16]Quintero et al introduced system fidelity factor (SFF) tocompare UWB antennas In [3] the half-spherical fidelityfactor pattern measurement results of Bowtie and Vivaldiantenna are presented The fidelity factor pattern describeshow does the signal vary in the different angular directionswith respect to the signal in the main beam direction In [17]Pancera and Wiesbeck introduced an optimization methodbased on the fidelity factor criterion to improve the radiationproperties of Bowtie antennas for medical applications
In this paper a method to improve the fidelity factor ofVivaldi antenna in spatial range is presented The originalVivaldi antenna operates in the frequency band 31ndash106GHzThemodified antenna has two dielectric slabs that are parallelto the antenna substrate These dielectric slabs are located ata distance 119889 from the upper and bottom faces of the antennaThe dielectric slabs act as a spatial filter to reform the signalwaveform Using the GA algorithm the parameters of thedielectric slabs have been optimized producing an incrementof the fidelity factor in a larger angular range The simu-lations of both original antenna and improved antenna areperformed using the commercial electromagnetic simulationsoftware CST MWS The available ranges with the fidelityfactor greater than the value of 09 in H-plane and in E-planeare improved by 95 and 14 respectivelyThe prototypes ofboth original antenna and improved antenna were fabricatedandmeasuredThe numerical results concerning the antennaparameters are found to be in good agreement with theexperimental measurements
2 Improvement of the Vivaldi AntennaFidelity Factor
21 Original Vivaldi Antenna Vivaldi antenna is one kindof classic end-fired directive travelling wave antennas whichhas a tapered slot characterized by a bell-shaped exponentialon it The slot curve on the substrate board becomes widergradually from the narrow end to thewide end and it radiatesthe electromagnetic waves using the corresponding part ofthe slot as constant electric size at the relevant frequency Sotheoretically Vivaldi antenna has an infinite wide frequency
Ws
x
y
0
Dielectric slab
119882119904
1198713
119871119904
(a)
0
y
x
d
t
Ant
enna
Die
lect
ric sl
ab(b)
Figure 6 Geometry of the improved Vivaldi antenna (a) top viewand (b) lateral view
band [5] In practice Vivaldi antenna has a band width betterthan 10 1 and has the features of low cross-polarization andhighly directive radiation patterns over the whole frequencyband In this paper a Vivaldi antenna operating in thefrequency band 31ndash106GHz is investigated The antenna isfabricated on a two-layer substrate with dielectric constantof 35 size of 85mmlowast70mm and each layer thickness of08mm The geometry of the original Vivaldi antenna isshown in Figure 1 with the xz-plane and yz-plane referred toas the E-plane and H-plane respectivelyThe reference frameadopted to express the field quantities is shown in Figure 2The tapers of the antennas are defined as
119909 = plusmn 119888119886sdot exp [119888
119887(119910 minus 10)] (1)
The values of the antenna geometrical parameters are shownin Table 1
A commercial Finite IntegrationTechnique (FIT) electro-magnetic simulation software CST MWS is used to analyzethe radiative performances of the Vivaldi antenna Theantenna is excited by aUWB signal in the frequency band 31ndash106GHz which is a Gaussian pulse in the frequency band 0ndash375GHzmodulated by a cosine wave carrier at the frequency
4 International Journal of Antennas and Propagation
minus90 minus70 minus50 minus30 3010minus10 50 70 900
010203040506070809
1
Improved antennaOriginal antenna
Fide
lity
fact
or in
H-p
lane
120579 (deg)
(a)
0010203040506070809
1
Fide
lity
fact
or in
E-p
lane
120579 (deg)
Improved antennaOriginal antenna
minus90 minus70 minus50 minus30 3010minus10 50 70 90
(b)
Figure 7 (a) Simulation results of fidelity factor in H-plane (120593 =90∘) and (b) simulation results of fidelity factor in E-plane (120593 = 0∘)
685GHz The waveform of excitation signal is shown inFigure 3 A set of probes have been placed at a distance of1000mm from the antenna on a plane around the antennaand spaced by 5 degrees to detect the time-domain signalradiated by the antenna Since the Vivaldi antenna has quitegood cross-polar property only the copolar radiation signalsare consideredThe normalized signal waveforms at themainbeam direction and other directions computed in the E- andH-planes are shown in Figures 4 and 5 respectively
The fidelity factor between the signal at the main beamdirection 119878
1(119905) and the signal in an arbitrary angular direction
1198782(119905) is defined as the normalized cross-correlation between
them and can be calculated by [3]
fidelity = max120591
int
+infin
minusinfin
1198781(119905 minus 120591) 119878
2(119905) 119889119905
radicint
+infin
minusinfin
10038171003817100381710038171198781(119905)1003817100381710038171003817
2
119889119905 int
+infin
minusinfin
10038171003817100381710038171198781(119905)1003817100381710038171003817
2
119889119905
(2)
(a)
(b)
Figure 8 (a) Picture of the original antenna and (b) picture of theimproved antenna
0 1 2 3 4 5 6 7 8 9 10 11 12 13minus40
minus35
minus30
minus25
minus20
minus15
minus10
minus5
0
MeasurementSimulation
|11987811|
(dB)
Frequency (GHz)
Figure 9 |11987811
| of improved antenna
The fidelity factor results computed in E- and H-planes arelisted in Table 2
From Table 2 it appears that the fidelity factor in H-planedegrades quickly as the angle between the antennarsquos mainbeam and the observation point is larger than 35 degrees
International Journal of Antennas and Propagation 5
Table 1 Geometrical parameters of the original Vivaldi antenna
Parameter Value Unit119882 70 mm119871 85 mm1198711
10 mm1198712
1225 mm119882119891
085 mm1198771
207 mm1198772
33 mm120572 46 ∘
119862119886
04440119862119887
00559
Table 2 Computed fidelity factor of the original antenna inH-planeand E-plane
H-plane (120593 = 90) E-plane (120593 = 0)120579 (degree) Fidelity factor 120579 (degree) Fidelity factor0 1 0 15 099998 5 09918210 099157 10 09915415 099012 15 09904020 098533 20 09875825 097260 25 09826330 094303 30 09762635 088816 35 09732040 077987 40 09700445 062700 45 09731850 046141 50 09755855 053453 55 09728860 053101 60 09615465 044638 65 09322670 034619 70 08661575 033003 75 07383080 035294 80 05776685 035444 85 063184
And this distortion will cause poor performance degradationwhile the beam is scanning out of this range
To improve the signal fidelity factor in a larger angularregion two dielectric slabs with relative dielectric constant120576119903and thickness 119905 which parallel the antenna substrate are
added to the original Vivaldi antenna The distance betweenthe slabs and antenna substrate is 119889 The structure of theproposed antenna is shown in Figure 6
The dielectric slabs play a role as a spatial filter whichhave the angular-dependant effect on the incident wave Soby proper tuning of 120576
119903 119905 and 119889 the quality of the radiated
wave can be restored This effect can be used to optimizethe antenna fidelity factor in the angular operational regionBesides the parameters above the length of the slabs 119871
119904and
the position of the slabs along the 119910-axis 1198713also can be
considered as optimization parameters because they decidethe angular range covered by the slabs
minus80 minus60 minus40 minus20 0 20 40 60 80
minus80
minus60
minus40
minus20
0
20
40
60
80
Azimuth angle (deg)
Elev
atio
n an
gle (
deg)
05
06
07
08
09
092
094
096
098
(a)
05
06
07
08
09
092
094
096
098
minus80 minus60 minus40 minus20 0 20 40 60 80
minus80
minus60
minus40
minus20
0
20
40
60
80
Azimuth (deg)
Elev
atio
n (d
eg)
(b)
Figure 10 (a) Fidelity factor test results of the original antenna and(b) fidelity factor test results of the improved antenna
3 Antenna Simulation and Measurement
The polyformaldehyde having a relative dielectric constant120576119903= 38 is chosen for the realization of the two dielectric
slabs thanks to its intrinsic characteristics consisting in theeasy machining and good temperature characteristics Thestructure of the Vivaldi antenna is optimized with the goalof the better fidelity factor in H-plane and in E-plane usingGenetic Algorithms optimizer in CSTMWSThe criterion ofthe fidelity factor is set to 09 The optimal parameters of thedielectric slabs are listed in Table 3
The fidelity factor of improved antenna computed in E-plane and H-plane is listed in Table 4 and compared with theresults of the original antenna as shown in Figure 7
The fidelity factor in H-plane has been improved signifi-cantly The available range of the original antenna in H-planeis 70 degrees and the improved antenna has an availablerange wider than 135 degrees which has been improved byabout 97 Besides that the available range in E-plane hasbeen improved from 136 degrees to 156 degrees which is notsuch remarkable as that in H-plane
6 International Journal of Antennas and Propagation
0010203040506070809
1
Improved antennaOriginal antenna
Fide
lity
fact
or in
H-p
lane
minus90 minus70 minus50 minus30 3010minus10 50 70 90120579 (deg)
(a)
0
010203040506070809
1
Fide
lity
fact
or in
E-p
lane
120579 (deg)
Improved antennaOriginal antenna
minus90 minus70 minus50 minus30 3010minus10 50 70 90
(b)
Figure 11 (a) Measurement results of fidelity factor in H-plane and(b) measurement results of fidelity factor in E-plane
Table 3 The geometrical parameters of the dielectric slabs
Parameter Value Unit119905 44 mm119882119904
40 mm1198713
43 mm119889 915 mm119871119904
70 mm
The prototypes of the two considered antennas are shownin Figure 8 while the numerical and measurement resultsconcerning the frequency behavior of the parameter |119878
11| of
the new antenna are reported in Figure 9The measurement of fidelity factor was carried out in
an enclosed anechoic chamber The measured antenna isinstalled on a rotating platform A wideband probe is used
Table 4 Fidelity factor of the improved antenna computed in E-plane and H-plane
H-plane (120593 = 90) E-plane (120593 = 0)120579 (degree) Fidelity factor 120579 (degree) Fidelity factor0 1 0 15 099995 5 09999510 098976 10 09997315 098881 15 09988820 098655 20 09970925 098285 25 09942130 097808 30 09902335 097300 35 09852140 097008 40 09790745 096478 45 09718650 095924 50 09650455 095839 55 09613760 095966 60 09624465 093783 65 09656670 086216 70 09615675 071946 75 09335180 049866 80 08640485 027054 85 074927
to receive the transient signal radiated by the antenna undertest when changing the azimuth and the elevation angle ofthe antennaThe fidelity factors calculated in the upper half-plane are plotted in Figure 10Themeasurement results of thefidelity factor in E-plane and H-plane are shown in Figure 11
The original Vivaldi antenna shows its good fidelity factorcharacteristics in a side-ways H-shape area with azimuthangle scanning less than 35 degrees in H-plane and elevationangle less than 65 degrees in E-plane respectively Theimproved Vivaldi antenna shows its good fidelity factorcharacteristics in a cross-shape area with azimuth anglescanning better than 65 degrees in H-plane and elevationangle better than 70 degrees in E-plane respectively whichis extended in horizontal direction significantly
4 Conclusion
In this paper a new method to improve the fidelity factorof a planar Vivaldi UWB antenna has been proposed Twodielectric slabs which play the role of a spatial filter suitableto restore the signal waveform in time domain are added tothe original Vivaldi antenna By tuning the dimensions andthe relative position of the dielectric slabs the fidelity factorin the half space is optimized The angular available range inH-plane with the fidelity factor greater than the value of 09has been improved by 95 and the available angular range inE-plane has been improved by 14
Acknowledgments
The authors would like to express their sincere gratitude toCSTLtd Germany for providing a free package of CSTMWS
International Journal of Antennas and Propagation 7
softwareThis workwas supported in part by the key programof the National Natural Science Foundation of China underGrant 61032003 and the National Basic Research Program ofChina under Grant 2009CB320402
References
[1] Y Q Zhang Y X Guo and M S Leong ldquoA novel multilayerUWB antenna on LTCCrdquo IEEE Transactions on Antennas andPropagation vol 58 no 9 pp 3013ndash3019 2010
[2] T A Vu M Z Dooghabadi S Sudalaiyandi et al ldquoUWBVivaldi antenna for impulse radio beamformingrdquo inProceedingsof the 27th Norchip Conference pp 1ndash5 Trondeim NorwayNovember 2009
[3] E Pancera T Zwick and W Wiesbeck ldquoSpherical fidelitypatterns of UWB antennasrdquo IEEE Transactions on Antennas andPropagation vol 59 no 6 pp 2111ndash2119 2011
[4] F Gross Frontiers in Antennas Next Generation Design ampEngineering McGraw-Hill 2011
[5] G Cappelletti D Caratelli R Cicchetti and M SimeonildquoA low profile printed drop-shaped dipole antenna for wide-band wireless applicationsrdquo IEEE Transactions on Antennas andPropagation vol 59 no 10 pp 3526ndash3535 2011
[6] A A Gheethan and D E Anagnostou ldquoDual band-reject UWBantenna with sharp rejection of narrow and closely-spacedbandsrdquo IEEETransactions onAntennas and Propagation vol 60no 4 pp 2071ndash2076 2012
[7] L Desrumaux A Godard M Lalande V Bertrand J Andrieuand B Jecko ldquoAn original antenna for transient high powerUWB arrays the Shark antennardquo IEEE Transactions on Anten-nas and Propagation vol 58 no 8 pp 2515ndash2522 2010
[8] L R LewisM Fassett and J Hunt ldquoA broadband stripline arrayelementrdquo in Proceedings of the IEEE Antennas and PropagationSymposium Digest pp 335ndash337 Atlanta Ga USA 1974
[9] Y Li and A Chen ldquoDesign and application of Vivaldi antennaarrayrdquo in Proceedings of the 8th International Symposium onAntennas Propagation andEMTheory (ISAPE rsquo08) pp 267ndash270Kunming China November 2008
[10] A Z Hood T Karacolak and E Topsakal ldquoA small antipodalvivaldi antenna for ultrawide-band applicationsrdquo IEEE Anten-nas and Wireless Propagation Letters vol 7 pp 656ndash660 2008
[11] J Bai S Shi and D W Prather ldquoUltra-wideband slot-loaded antipodal Vivaldi antenna arrayrdquo in Proceedings of theIEEE International Symposium on Antennas and Propagation(APSURSI rsquo11) pp 79ndash81 Spokane Wash USA 2011
[12] J Zhang J Wang and W Hu ldquoAnalysis of UWB signal distor-tion in transmittingreceiving antenna systemsrdquo in Proceedingsof the 9th International Symposium on Antennas Propagationand EM Theory (ISAPE rsquo10) pp 163ndash166 Guangzhou ChinaDecember 2010
[13] K Trott B Cummings R Cavener M Deluca J Biondi andT Sikina ldquoWideband phased array radiatorrdquo in Proceedings ofthe IEEE International Symposium on Phased Array Systems ampTechnology pp 383ndash386 Boston Mass USA October 2003
[14] D Carsenat and C Decroze ldquoUWB antennas beamformingusing passive time-reversal devicerdquo IEEE Antennas andWirelessPropagation Letters vol 11 pp 779ndash782 2012
[15] M A Elmansouri andD S Filipovic ldquoPulse distortion andmit-igation thereof in spiral antenna-based UWB communicationsystemsrdquo IEEE Antennas and Wireless Propagation Letters vol59 no 10 pp 3863ndash3871 2011
[16] G Quintero J F Zurcher and A K Skrivervik ldquoSystem fidelityfactor a new method for comparing UWB antennasrdquo IEEETransactions on Antennas and Propagation vol 59 no 7 pp2502ndash2512 2011
[17] E Pancera and W Wiesbeck ldquoFidelity based optimization ofUWB antenna-radiation for medical applicationsrdquo in Proceed-ings of the IEEE International Symposium on Antennas andPropagation (APSURSI rsquo11) p 2411 Spokane Wash USA July2011
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of
International Journal of Antennas and Propagation 3
impedance performance of Vivaldi antenna arrays which arewidely used in modern electronic warfare system and radarsystem [13 14]
It is quite important for an antenna array element tokeep good performance in a wide spatial region whilethe main beam is scanning In practice all the antennasradiate different signals in different spatial directions Soit is quite important to study the correlation between thesignal radiated and spatial directions both in frequencyand in time domains In [15] the angular distortion of thesignal radiated with respect to that emitted in the mainbeam direction of UWB antennas has been investigated Thecorrelation properties of the pulse signals are determinedby the so-called fidelity factor It can be quantified throughthe analysis of the correlation between the signal in anarbitrary angular direction and the signal in the main beamdirection Usually a fidelity factor which is greater than thevalue of 09 could be considered to be acceptable In [16]Quintero et al introduced system fidelity factor (SFF) tocompare UWB antennas In [3] the half-spherical fidelityfactor pattern measurement results of Bowtie and Vivaldiantenna are presented The fidelity factor pattern describeshow does the signal vary in the different angular directionswith respect to the signal in the main beam direction In [17]Pancera and Wiesbeck introduced an optimization methodbased on the fidelity factor criterion to improve the radiationproperties of Bowtie antennas for medical applications
In this paper a method to improve the fidelity factor ofVivaldi antenna in spatial range is presented The originalVivaldi antenna operates in the frequency band 31ndash106GHzThemodified antenna has two dielectric slabs that are parallelto the antenna substrate These dielectric slabs are located ata distance 119889 from the upper and bottom faces of the antennaThe dielectric slabs act as a spatial filter to reform the signalwaveform Using the GA algorithm the parameters of thedielectric slabs have been optimized producing an incrementof the fidelity factor in a larger angular range The simu-lations of both original antenna and improved antenna areperformed using the commercial electromagnetic simulationsoftware CST MWS The available ranges with the fidelityfactor greater than the value of 09 in H-plane and in E-planeare improved by 95 and 14 respectivelyThe prototypes ofboth original antenna and improved antenna were fabricatedandmeasuredThe numerical results concerning the antennaparameters are found to be in good agreement with theexperimental measurements
2 Improvement of the Vivaldi AntennaFidelity Factor
21 Original Vivaldi Antenna Vivaldi antenna is one kindof classic end-fired directive travelling wave antennas whichhas a tapered slot characterized by a bell-shaped exponentialon it The slot curve on the substrate board becomes widergradually from the narrow end to thewide end and it radiatesthe electromagnetic waves using the corresponding part ofthe slot as constant electric size at the relevant frequency Sotheoretically Vivaldi antenna has an infinite wide frequency
Ws
x
y
0
Dielectric slab
119882119904
1198713
119871119904
(a)
0
y
x
d
t
Ant
enna
Die
lect
ric sl
ab(b)
Figure 6 Geometry of the improved Vivaldi antenna (a) top viewand (b) lateral view
band [5] In practice Vivaldi antenna has a band width betterthan 10 1 and has the features of low cross-polarization andhighly directive radiation patterns over the whole frequencyband In this paper a Vivaldi antenna operating in thefrequency band 31ndash106GHz is investigated The antenna isfabricated on a two-layer substrate with dielectric constantof 35 size of 85mmlowast70mm and each layer thickness of08mm The geometry of the original Vivaldi antenna isshown in Figure 1 with the xz-plane and yz-plane referred toas the E-plane and H-plane respectivelyThe reference frameadopted to express the field quantities is shown in Figure 2The tapers of the antennas are defined as
119909 = plusmn 119888119886sdot exp [119888
119887(119910 minus 10)] (1)
The values of the antenna geometrical parameters are shownin Table 1
A commercial Finite IntegrationTechnique (FIT) electro-magnetic simulation software CST MWS is used to analyzethe radiative performances of the Vivaldi antenna Theantenna is excited by aUWB signal in the frequency band 31ndash106GHz which is a Gaussian pulse in the frequency band 0ndash375GHzmodulated by a cosine wave carrier at the frequency
4 International Journal of Antennas and Propagation
minus90 minus70 minus50 minus30 3010minus10 50 70 900
010203040506070809
1
Improved antennaOriginal antenna
Fide
lity
fact
or in
H-p
lane
120579 (deg)
(a)
0010203040506070809
1
Fide
lity
fact
or in
E-p
lane
120579 (deg)
Improved antennaOriginal antenna
minus90 minus70 minus50 minus30 3010minus10 50 70 90
(b)
Figure 7 (a) Simulation results of fidelity factor in H-plane (120593 =90∘) and (b) simulation results of fidelity factor in E-plane (120593 = 0∘)
685GHz The waveform of excitation signal is shown inFigure 3 A set of probes have been placed at a distance of1000mm from the antenna on a plane around the antennaand spaced by 5 degrees to detect the time-domain signalradiated by the antenna Since the Vivaldi antenna has quitegood cross-polar property only the copolar radiation signalsare consideredThe normalized signal waveforms at themainbeam direction and other directions computed in the E- andH-planes are shown in Figures 4 and 5 respectively
The fidelity factor between the signal at the main beamdirection 119878
1(119905) and the signal in an arbitrary angular direction
1198782(119905) is defined as the normalized cross-correlation between
them and can be calculated by [3]
fidelity = max120591
int
+infin
minusinfin
1198781(119905 minus 120591) 119878
2(119905) 119889119905
radicint
+infin
minusinfin
10038171003817100381710038171198781(119905)1003817100381710038171003817
2
119889119905 int
+infin
minusinfin
10038171003817100381710038171198781(119905)1003817100381710038171003817
2
119889119905
(2)
(a)
(b)
Figure 8 (a) Picture of the original antenna and (b) picture of theimproved antenna
0 1 2 3 4 5 6 7 8 9 10 11 12 13minus40
minus35
minus30
minus25
minus20
minus15
minus10
minus5
0
MeasurementSimulation
|11987811|
(dB)
Frequency (GHz)
Figure 9 |11987811
| of improved antenna
The fidelity factor results computed in E- and H-planes arelisted in Table 2
From Table 2 it appears that the fidelity factor in H-planedegrades quickly as the angle between the antennarsquos mainbeam and the observation point is larger than 35 degrees
International Journal of Antennas and Propagation 5
Table 1 Geometrical parameters of the original Vivaldi antenna
Parameter Value Unit119882 70 mm119871 85 mm1198711
10 mm1198712
1225 mm119882119891
085 mm1198771
207 mm1198772
33 mm120572 46 ∘
119862119886
04440119862119887
00559
Table 2 Computed fidelity factor of the original antenna inH-planeand E-plane
H-plane (120593 = 90) E-plane (120593 = 0)120579 (degree) Fidelity factor 120579 (degree) Fidelity factor0 1 0 15 099998 5 09918210 099157 10 09915415 099012 15 09904020 098533 20 09875825 097260 25 09826330 094303 30 09762635 088816 35 09732040 077987 40 09700445 062700 45 09731850 046141 50 09755855 053453 55 09728860 053101 60 09615465 044638 65 09322670 034619 70 08661575 033003 75 07383080 035294 80 05776685 035444 85 063184
And this distortion will cause poor performance degradationwhile the beam is scanning out of this range
To improve the signal fidelity factor in a larger angularregion two dielectric slabs with relative dielectric constant120576119903and thickness 119905 which parallel the antenna substrate are
added to the original Vivaldi antenna The distance betweenthe slabs and antenna substrate is 119889 The structure of theproposed antenna is shown in Figure 6
The dielectric slabs play a role as a spatial filter whichhave the angular-dependant effect on the incident wave Soby proper tuning of 120576
119903 119905 and 119889 the quality of the radiated
wave can be restored This effect can be used to optimizethe antenna fidelity factor in the angular operational regionBesides the parameters above the length of the slabs 119871
119904and
the position of the slabs along the 119910-axis 1198713also can be
considered as optimization parameters because they decidethe angular range covered by the slabs
minus80 minus60 minus40 minus20 0 20 40 60 80
minus80
minus60
minus40
minus20
0
20
40
60
80
Azimuth angle (deg)
Elev
atio
n an
gle (
deg)
05
06
07
08
09
092
094
096
098
(a)
05
06
07
08
09
092
094
096
098
minus80 minus60 minus40 minus20 0 20 40 60 80
minus80
minus60
minus40
minus20
0
20
40
60
80
Azimuth (deg)
Elev
atio
n (d
eg)
(b)
Figure 10 (a) Fidelity factor test results of the original antenna and(b) fidelity factor test results of the improved antenna
3 Antenna Simulation and Measurement
The polyformaldehyde having a relative dielectric constant120576119903= 38 is chosen for the realization of the two dielectric
slabs thanks to its intrinsic characteristics consisting in theeasy machining and good temperature characteristics Thestructure of the Vivaldi antenna is optimized with the goalof the better fidelity factor in H-plane and in E-plane usingGenetic Algorithms optimizer in CSTMWSThe criterion ofthe fidelity factor is set to 09 The optimal parameters of thedielectric slabs are listed in Table 3
The fidelity factor of improved antenna computed in E-plane and H-plane is listed in Table 4 and compared with theresults of the original antenna as shown in Figure 7
The fidelity factor in H-plane has been improved signifi-cantly The available range of the original antenna in H-planeis 70 degrees and the improved antenna has an availablerange wider than 135 degrees which has been improved byabout 97 Besides that the available range in E-plane hasbeen improved from 136 degrees to 156 degrees which is notsuch remarkable as that in H-plane
6 International Journal of Antennas and Propagation
0010203040506070809
1
Improved antennaOriginal antenna
Fide
lity
fact
or in
H-p
lane
minus90 minus70 minus50 minus30 3010minus10 50 70 90120579 (deg)
(a)
0
010203040506070809
1
Fide
lity
fact
or in
E-p
lane
120579 (deg)
Improved antennaOriginal antenna
minus90 minus70 minus50 minus30 3010minus10 50 70 90
(b)
Figure 11 (a) Measurement results of fidelity factor in H-plane and(b) measurement results of fidelity factor in E-plane
Table 3 The geometrical parameters of the dielectric slabs
Parameter Value Unit119905 44 mm119882119904
40 mm1198713
43 mm119889 915 mm119871119904
70 mm
The prototypes of the two considered antennas are shownin Figure 8 while the numerical and measurement resultsconcerning the frequency behavior of the parameter |119878
11| of
the new antenna are reported in Figure 9The measurement of fidelity factor was carried out in
an enclosed anechoic chamber The measured antenna isinstalled on a rotating platform A wideband probe is used
Table 4 Fidelity factor of the improved antenna computed in E-plane and H-plane
H-plane (120593 = 90) E-plane (120593 = 0)120579 (degree) Fidelity factor 120579 (degree) Fidelity factor0 1 0 15 099995 5 09999510 098976 10 09997315 098881 15 09988820 098655 20 09970925 098285 25 09942130 097808 30 09902335 097300 35 09852140 097008 40 09790745 096478 45 09718650 095924 50 09650455 095839 55 09613760 095966 60 09624465 093783 65 09656670 086216 70 09615675 071946 75 09335180 049866 80 08640485 027054 85 074927
to receive the transient signal radiated by the antenna undertest when changing the azimuth and the elevation angle ofthe antennaThe fidelity factors calculated in the upper half-plane are plotted in Figure 10Themeasurement results of thefidelity factor in E-plane and H-plane are shown in Figure 11
The original Vivaldi antenna shows its good fidelity factorcharacteristics in a side-ways H-shape area with azimuthangle scanning less than 35 degrees in H-plane and elevationangle less than 65 degrees in E-plane respectively Theimproved Vivaldi antenna shows its good fidelity factorcharacteristics in a cross-shape area with azimuth anglescanning better than 65 degrees in H-plane and elevationangle better than 70 degrees in E-plane respectively whichis extended in horizontal direction significantly
4 Conclusion
In this paper a new method to improve the fidelity factorof a planar Vivaldi UWB antenna has been proposed Twodielectric slabs which play the role of a spatial filter suitableto restore the signal waveform in time domain are added tothe original Vivaldi antenna By tuning the dimensions andthe relative position of the dielectric slabs the fidelity factorin the half space is optimized The angular available range inH-plane with the fidelity factor greater than the value of 09has been improved by 95 and the available angular range inE-plane has been improved by 14
Acknowledgments
The authors would like to express their sincere gratitude toCSTLtd Germany for providing a free package of CSTMWS
International Journal of Antennas and Propagation 7
softwareThis workwas supported in part by the key programof the National Natural Science Foundation of China underGrant 61032003 and the National Basic Research Program ofChina under Grant 2009CB320402
References
[1] Y Q Zhang Y X Guo and M S Leong ldquoA novel multilayerUWB antenna on LTCCrdquo IEEE Transactions on Antennas andPropagation vol 58 no 9 pp 3013ndash3019 2010
[2] T A Vu M Z Dooghabadi S Sudalaiyandi et al ldquoUWBVivaldi antenna for impulse radio beamformingrdquo inProceedingsof the 27th Norchip Conference pp 1ndash5 Trondeim NorwayNovember 2009
[3] E Pancera T Zwick and W Wiesbeck ldquoSpherical fidelitypatterns of UWB antennasrdquo IEEE Transactions on Antennas andPropagation vol 59 no 6 pp 2111ndash2119 2011
[4] F Gross Frontiers in Antennas Next Generation Design ampEngineering McGraw-Hill 2011
[5] G Cappelletti D Caratelli R Cicchetti and M SimeonildquoA low profile printed drop-shaped dipole antenna for wide-band wireless applicationsrdquo IEEE Transactions on Antennas andPropagation vol 59 no 10 pp 3526ndash3535 2011
[6] A A Gheethan and D E Anagnostou ldquoDual band-reject UWBantenna with sharp rejection of narrow and closely-spacedbandsrdquo IEEETransactions onAntennas and Propagation vol 60no 4 pp 2071ndash2076 2012
[7] L Desrumaux A Godard M Lalande V Bertrand J Andrieuand B Jecko ldquoAn original antenna for transient high powerUWB arrays the Shark antennardquo IEEE Transactions on Anten-nas and Propagation vol 58 no 8 pp 2515ndash2522 2010
[8] L R LewisM Fassett and J Hunt ldquoA broadband stripline arrayelementrdquo in Proceedings of the IEEE Antennas and PropagationSymposium Digest pp 335ndash337 Atlanta Ga USA 1974
[9] Y Li and A Chen ldquoDesign and application of Vivaldi antennaarrayrdquo in Proceedings of the 8th International Symposium onAntennas Propagation andEMTheory (ISAPE rsquo08) pp 267ndash270Kunming China November 2008
[10] A Z Hood T Karacolak and E Topsakal ldquoA small antipodalvivaldi antenna for ultrawide-band applicationsrdquo IEEE Anten-nas and Wireless Propagation Letters vol 7 pp 656ndash660 2008
[11] J Bai S Shi and D W Prather ldquoUltra-wideband slot-loaded antipodal Vivaldi antenna arrayrdquo in Proceedings of theIEEE International Symposium on Antennas and Propagation(APSURSI rsquo11) pp 79ndash81 Spokane Wash USA 2011
[12] J Zhang J Wang and W Hu ldquoAnalysis of UWB signal distor-tion in transmittingreceiving antenna systemsrdquo in Proceedingsof the 9th International Symposium on Antennas Propagationand EM Theory (ISAPE rsquo10) pp 163ndash166 Guangzhou ChinaDecember 2010
[13] K Trott B Cummings R Cavener M Deluca J Biondi andT Sikina ldquoWideband phased array radiatorrdquo in Proceedings ofthe IEEE International Symposium on Phased Array Systems ampTechnology pp 383ndash386 Boston Mass USA October 2003
[14] D Carsenat and C Decroze ldquoUWB antennas beamformingusing passive time-reversal devicerdquo IEEE Antennas andWirelessPropagation Letters vol 11 pp 779ndash782 2012
[15] M A Elmansouri andD S Filipovic ldquoPulse distortion andmit-igation thereof in spiral antenna-based UWB communicationsystemsrdquo IEEE Antennas and Wireless Propagation Letters vol59 no 10 pp 3863ndash3871 2011
[16] G Quintero J F Zurcher and A K Skrivervik ldquoSystem fidelityfactor a new method for comparing UWB antennasrdquo IEEETransactions on Antennas and Propagation vol 59 no 7 pp2502ndash2512 2011
[17] E Pancera and W Wiesbeck ldquoFidelity based optimization ofUWB antenna-radiation for medical applicationsrdquo in Proceed-ings of the IEEE International Symposium on Antennas andPropagation (APSURSI rsquo11) p 2411 Spokane Wash USA July2011
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of
4 International Journal of Antennas and Propagation
minus90 minus70 minus50 minus30 3010minus10 50 70 900
010203040506070809
1
Improved antennaOriginal antenna
Fide
lity
fact
or in
H-p
lane
120579 (deg)
(a)
0010203040506070809
1
Fide
lity
fact
or in
E-p
lane
120579 (deg)
Improved antennaOriginal antenna
minus90 minus70 minus50 minus30 3010minus10 50 70 90
(b)
Figure 7 (a) Simulation results of fidelity factor in H-plane (120593 =90∘) and (b) simulation results of fidelity factor in E-plane (120593 = 0∘)
685GHz The waveform of excitation signal is shown inFigure 3 A set of probes have been placed at a distance of1000mm from the antenna on a plane around the antennaand spaced by 5 degrees to detect the time-domain signalradiated by the antenna Since the Vivaldi antenna has quitegood cross-polar property only the copolar radiation signalsare consideredThe normalized signal waveforms at themainbeam direction and other directions computed in the E- andH-planes are shown in Figures 4 and 5 respectively
The fidelity factor between the signal at the main beamdirection 119878
1(119905) and the signal in an arbitrary angular direction
1198782(119905) is defined as the normalized cross-correlation between
them and can be calculated by [3]
fidelity = max120591
int
+infin
minusinfin
1198781(119905 minus 120591) 119878
2(119905) 119889119905
radicint
+infin
minusinfin
10038171003817100381710038171198781(119905)1003817100381710038171003817
2
119889119905 int
+infin
minusinfin
10038171003817100381710038171198781(119905)1003817100381710038171003817
2
119889119905
(2)
(a)
(b)
Figure 8 (a) Picture of the original antenna and (b) picture of theimproved antenna
0 1 2 3 4 5 6 7 8 9 10 11 12 13minus40
minus35
minus30
minus25
minus20
minus15
minus10
minus5
0
MeasurementSimulation
|11987811|
(dB)
Frequency (GHz)
Figure 9 |11987811
| of improved antenna
The fidelity factor results computed in E- and H-planes arelisted in Table 2
From Table 2 it appears that the fidelity factor in H-planedegrades quickly as the angle between the antennarsquos mainbeam and the observation point is larger than 35 degrees
International Journal of Antennas and Propagation 5
Table 1 Geometrical parameters of the original Vivaldi antenna
Parameter Value Unit119882 70 mm119871 85 mm1198711
10 mm1198712
1225 mm119882119891
085 mm1198771
207 mm1198772
33 mm120572 46 ∘
119862119886
04440119862119887
00559
Table 2 Computed fidelity factor of the original antenna inH-planeand E-plane
H-plane (120593 = 90) E-plane (120593 = 0)120579 (degree) Fidelity factor 120579 (degree) Fidelity factor0 1 0 15 099998 5 09918210 099157 10 09915415 099012 15 09904020 098533 20 09875825 097260 25 09826330 094303 30 09762635 088816 35 09732040 077987 40 09700445 062700 45 09731850 046141 50 09755855 053453 55 09728860 053101 60 09615465 044638 65 09322670 034619 70 08661575 033003 75 07383080 035294 80 05776685 035444 85 063184
And this distortion will cause poor performance degradationwhile the beam is scanning out of this range
To improve the signal fidelity factor in a larger angularregion two dielectric slabs with relative dielectric constant120576119903and thickness 119905 which parallel the antenna substrate are
added to the original Vivaldi antenna The distance betweenthe slabs and antenna substrate is 119889 The structure of theproposed antenna is shown in Figure 6
The dielectric slabs play a role as a spatial filter whichhave the angular-dependant effect on the incident wave Soby proper tuning of 120576
119903 119905 and 119889 the quality of the radiated
wave can be restored This effect can be used to optimizethe antenna fidelity factor in the angular operational regionBesides the parameters above the length of the slabs 119871
119904and
the position of the slabs along the 119910-axis 1198713also can be
considered as optimization parameters because they decidethe angular range covered by the slabs
minus80 minus60 minus40 minus20 0 20 40 60 80
minus80
minus60
minus40
minus20
0
20
40
60
80
Azimuth angle (deg)
Elev
atio
n an
gle (
deg)
05
06
07
08
09
092
094
096
098
(a)
05
06
07
08
09
092
094
096
098
minus80 minus60 minus40 minus20 0 20 40 60 80
minus80
minus60
minus40
minus20
0
20
40
60
80
Azimuth (deg)
Elev
atio
n (d
eg)
(b)
Figure 10 (a) Fidelity factor test results of the original antenna and(b) fidelity factor test results of the improved antenna
3 Antenna Simulation and Measurement
The polyformaldehyde having a relative dielectric constant120576119903= 38 is chosen for the realization of the two dielectric
slabs thanks to its intrinsic characteristics consisting in theeasy machining and good temperature characteristics Thestructure of the Vivaldi antenna is optimized with the goalof the better fidelity factor in H-plane and in E-plane usingGenetic Algorithms optimizer in CSTMWSThe criterion ofthe fidelity factor is set to 09 The optimal parameters of thedielectric slabs are listed in Table 3
The fidelity factor of improved antenna computed in E-plane and H-plane is listed in Table 4 and compared with theresults of the original antenna as shown in Figure 7
The fidelity factor in H-plane has been improved signifi-cantly The available range of the original antenna in H-planeis 70 degrees and the improved antenna has an availablerange wider than 135 degrees which has been improved byabout 97 Besides that the available range in E-plane hasbeen improved from 136 degrees to 156 degrees which is notsuch remarkable as that in H-plane
6 International Journal of Antennas and Propagation
0010203040506070809
1
Improved antennaOriginal antenna
Fide
lity
fact
or in
H-p
lane
minus90 minus70 minus50 minus30 3010minus10 50 70 90120579 (deg)
(a)
0
010203040506070809
1
Fide
lity
fact
or in
E-p
lane
120579 (deg)
Improved antennaOriginal antenna
minus90 minus70 minus50 minus30 3010minus10 50 70 90
(b)
Figure 11 (a) Measurement results of fidelity factor in H-plane and(b) measurement results of fidelity factor in E-plane
Table 3 The geometrical parameters of the dielectric slabs
Parameter Value Unit119905 44 mm119882119904
40 mm1198713
43 mm119889 915 mm119871119904
70 mm
The prototypes of the two considered antennas are shownin Figure 8 while the numerical and measurement resultsconcerning the frequency behavior of the parameter |119878
11| of
the new antenna are reported in Figure 9The measurement of fidelity factor was carried out in
an enclosed anechoic chamber The measured antenna isinstalled on a rotating platform A wideband probe is used
Table 4 Fidelity factor of the improved antenna computed in E-plane and H-plane
H-plane (120593 = 90) E-plane (120593 = 0)120579 (degree) Fidelity factor 120579 (degree) Fidelity factor0 1 0 15 099995 5 09999510 098976 10 09997315 098881 15 09988820 098655 20 09970925 098285 25 09942130 097808 30 09902335 097300 35 09852140 097008 40 09790745 096478 45 09718650 095924 50 09650455 095839 55 09613760 095966 60 09624465 093783 65 09656670 086216 70 09615675 071946 75 09335180 049866 80 08640485 027054 85 074927
to receive the transient signal radiated by the antenna undertest when changing the azimuth and the elevation angle ofthe antennaThe fidelity factors calculated in the upper half-plane are plotted in Figure 10Themeasurement results of thefidelity factor in E-plane and H-plane are shown in Figure 11
The original Vivaldi antenna shows its good fidelity factorcharacteristics in a side-ways H-shape area with azimuthangle scanning less than 35 degrees in H-plane and elevationangle less than 65 degrees in E-plane respectively Theimproved Vivaldi antenna shows its good fidelity factorcharacteristics in a cross-shape area with azimuth anglescanning better than 65 degrees in H-plane and elevationangle better than 70 degrees in E-plane respectively whichis extended in horizontal direction significantly
4 Conclusion
In this paper a new method to improve the fidelity factorof a planar Vivaldi UWB antenna has been proposed Twodielectric slabs which play the role of a spatial filter suitableto restore the signal waveform in time domain are added tothe original Vivaldi antenna By tuning the dimensions andthe relative position of the dielectric slabs the fidelity factorin the half space is optimized The angular available range inH-plane with the fidelity factor greater than the value of 09has been improved by 95 and the available angular range inE-plane has been improved by 14
Acknowledgments
The authors would like to express their sincere gratitude toCSTLtd Germany for providing a free package of CSTMWS
International Journal of Antennas and Propagation 7
softwareThis workwas supported in part by the key programof the National Natural Science Foundation of China underGrant 61032003 and the National Basic Research Program ofChina under Grant 2009CB320402
References
[1] Y Q Zhang Y X Guo and M S Leong ldquoA novel multilayerUWB antenna on LTCCrdquo IEEE Transactions on Antennas andPropagation vol 58 no 9 pp 3013ndash3019 2010
[2] T A Vu M Z Dooghabadi S Sudalaiyandi et al ldquoUWBVivaldi antenna for impulse radio beamformingrdquo inProceedingsof the 27th Norchip Conference pp 1ndash5 Trondeim NorwayNovember 2009
[3] E Pancera T Zwick and W Wiesbeck ldquoSpherical fidelitypatterns of UWB antennasrdquo IEEE Transactions on Antennas andPropagation vol 59 no 6 pp 2111ndash2119 2011
[4] F Gross Frontiers in Antennas Next Generation Design ampEngineering McGraw-Hill 2011
[5] G Cappelletti D Caratelli R Cicchetti and M SimeonildquoA low profile printed drop-shaped dipole antenna for wide-band wireless applicationsrdquo IEEE Transactions on Antennas andPropagation vol 59 no 10 pp 3526ndash3535 2011
[6] A A Gheethan and D E Anagnostou ldquoDual band-reject UWBantenna with sharp rejection of narrow and closely-spacedbandsrdquo IEEETransactions onAntennas and Propagation vol 60no 4 pp 2071ndash2076 2012
[7] L Desrumaux A Godard M Lalande V Bertrand J Andrieuand B Jecko ldquoAn original antenna for transient high powerUWB arrays the Shark antennardquo IEEE Transactions on Anten-nas and Propagation vol 58 no 8 pp 2515ndash2522 2010
[8] L R LewisM Fassett and J Hunt ldquoA broadband stripline arrayelementrdquo in Proceedings of the IEEE Antennas and PropagationSymposium Digest pp 335ndash337 Atlanta Ga USA 1974
[9] Y Li and A Chen ldquoDesign and application of Vivaldi antennaarrayrdquo in Proceedings of the 8th International Symposium onAntennas Propagation andEMTheory (ISAPE rsquo08) pp 267ndash270Kunming China November 2008
[10] A Z Hood T Karacolak and E Topsakal ldquoA small antipodalvivaldi antenna for ultrawide-band applicationsrdquo IEEE Anten-nas and Wireless Propagation Letters vol 7 pp 656ndash660 2008
[11] J Bai S Shi and D W Prather ldquoUltra-wideband slot-loaded antipodal Vivaldi antenna arrayrdquo in Proceedings of theIEEE International Symposium on Antennas and Propagation(APSURSI rsquo11) pp 79ndash81 Spokane Wash USA 2011
[12] J Zhang J Wang and W Hu ldquoAnalysis of UWB signal distor-tion in transmittingreceiving antenna systemsrdquo in Proceedingsof the 9th International Symposium on Antennas Propagationand EM Theory (ISAPE rsquo10) pp 163ndash166 Guangzhou ChinaDecember 2010
[13] K Trott B Cummings R Cavener M Deluca J Biondi andT Sikina ldquoWideband phased array radiatorrdquo in Proceedings ofthe IEEE International Symposium on Phased Array Systems ampTechnology pp 383ndash386 Boston Mass USA October 2003
[14] D Carsenat and C Decroze ldquoUWB antennas beamformingusing passive time-reversal devicerdquo IEEE Antennas andWirelessPropagation Letters vol 11 pp 779ndash782 2012
[15] M A Elmansouri andD S Filipovic ldquoPulse distortion andmit-igation thereof in spiral antenna-based UWB communicationsystemsrdquo IEEE Antennas and Wireless Propagation Letters vol59 no 10 pp 3863ndash3871 2011
[16] G Quintero J F Zurcher and A K Skrivervik ldquoSystem fidelityfactor a new method for comparing UWB antennasrdquo IEEETransactions on Antennas and Propagation vol 59 no 7 pp2502ndash2512 2011
[17] E Pancera and W Wiesbeck ldquoFidelity based optimization ofUWB antenna-radiation for medical applicationsrdquo in Proceed-ings of the IEEE International Symposium on Antennas andPropagation (APSURSI rsquo11) p 2411 Spokane Wash USA July2011
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of
International Journal of Antennas and Propagation 5
Table 1 Geometrical parameters of the original Vivaldi antenna
Parameter Value Unit119882 70 mm119871 85 mm1198711
10 mm1198712
1225 mm119882119891
085 mm1198771
207 mm1198772
33 mm120572 46 ∘
119862119886
04440119862119887
00559
Table 2 Computed fidelity factor of the original antenna inH-planeand E-plane
H-plane (120593 = 90) E-plane (120593 = 0)120579 (degree) Fidelity factor 120579 (degree) Fidelity factor0 1 0 15 099998 5 09918210 099157 10 09915415 099012 15 09904020 098533 20 09875825 097260 25 09826330 094303 30 09762635 088816 35 09732040 077987 40 09700445 062700 45 09731850 046141 50 09755855 053453 55 09728860 053101 60 09615465 044638 65 09322670 034619 70 08661575 033003 75 07383080 035294 80 05776685 035444 85 063184
And this distortion will cause poor performance degradationwhile the beam is scanning out of this range
To improve the signal fidelity factor in a larger angularregion two dielectric slabs with relative dielectric constant120576119903and thickness 119905 which parallel the antenna substrate are
added to the original Vivaldi antenna The distance betweenthe slabs and antenna substrate is 119889 The structure of theproposed antenna is shown in Figure 6
The dielectric slabs play a role as a spatial filter whichhave the angular-dependant effect on the incident wave Soby proper tuning of 120576
119903 119905 and 119889 the quality of the radiated
wave can be restored This effect can be used to optimizethe antenna fidelity factor in the angular operational regionBesides the parameters above the length of the slabs 119871
119904and
the position of the slabs along the 119910-axis 1198713also can be
considered as optimization parameters because they decidethe angular range covered by the slabs
minus80 minus60 minus40 minus20 0 20 40 60 80
minus80
minus60
minus40
minus20
0
20
40
60
80
Azimuth angle (deg)
Elev
atio
n an
gle (
deg)
05
06
07
08
09
092
094
096
098
(a)
05
06
07
08
09
092
094
096
098
minus80 minus60 minus40 minus20 0 20 40 60 80
minus80
minus60
minus40
minus20
0
20
40
60
80
Azimuth (deg)
Elev
atio
n (d
eg)
(b)
Figure 10 (a) Fidelity factor test results of the original antenna and(b) fidelity factor test results of the improved antenna
3 Antenna Simulation and Measurement
The polyformaldehyde having a relative dielectric constant120576119903= 38 is chosen for the realization of the two dielectric
slabs thanks to its intrinsic characteristics consisting in theeasy machining and good temperature characteristics Thestructure of the Vivaldi antenna is optimized with the goalof the better fidelity factor in H-plane and in E-plane usingGenetic Algorithms optimizer in CSTMWSThe criterion ofthe fidelity factor is set to 09 The optimal parameters of thedielectric slabs are listed in Table 3
The fidelity factor of improved antenna computed in E-plane and H-plane is listed in Table 4 and compared with theresults of the original antenna as shown in Figure 7
The fidelity factor in H-plane has been improved signifi-cantly The available range of the original antenna in H-planeis 70 degrees and the improved antenna has an availablerange wider than 135 degrees which has been improved byabout 97 Besides that the available range in E-plane hasbeen improved from 136 degrees to 156 degrees which is notsuch remarkable as that in H-plane
6 International Journal of Antennas and Propagation
0010203040506070809
1
Improved antennaOriginal antenna
Fide
lity
fact
or in
H-p
lane
minus90 minus70 minus50 minus30 3010minus10 50 70 90120579 (deg)
(a)
0
010203040506070809
1
Fide
lity
fact
or in
E-p
lane
120579 (deg)
Improved antennaOriginal antenna
minus90 minus70 minus50 minus30 3010minus10 50 70 90
(b)
Figure 11 (a) Measurement results of fidelity factor in H-plane and(b) measurement results of fidelity factor in E-plane
Table 3 The geometrical parameters of the dielectric slabs
Parameter Value Unit119905 44 mm119882119904
40 mm1198713
43 mm119889 915 mm119871119904
70 mm
The prototypes of the two considered antennas are shownin Figure 8 while the numerical and measurement resultsconcerning the frequency behavior of the parameter |119878
11| of
the new antenna are reported in Figure 9The measurement of fidelity factor was carried out in
an enclosed anechoic chamber The measured antenna isinstalled on a rotating platform A wideband probe is used
Table 4 Fidelity factor of the improved antenna computed in E-plane and H-plane
H-plane (120593 = 90) E-plane (120593 = 0)120579 (degree) Fidelity factor 120579 (degree) Fidelity factor0 1 0 15 099995 5 09999510 098976 10 09997315 098881 15 09988820 098655 20 09970925 098285 25 09942130 097808 30 09902335 097300 35 09852140 097008 40 09790745 096478 45 09718650 095924 50 09650455 095839 55 09613760 095966 60 09624465 093783 65 09656670 086216 70 09615675 071946 75 09335180 049866 80 08640485 027054 85 074927
to receive the transient signal radiated by the antenna undertest when changing the azimuth and the elevation angle ofthe antennaThe fidelity factors calculated in the upper half-plane are plotted in Figure 10Themeasurement results of thefidelity factor in E-plane and H-plane are shown in Figure 11
The original Vivaldi antenna shows its good fidelity factorcharacteristics in a side-ways H-shape area with azimuthangle scanning less than 35 degrees in H-plane and elevationangle less than 65 degrees in E-plane respectively Theimproved Vivaldi antenna shows its good fidelity factorcharacteristics in a cross-shape area with azimuth anglescanning better than 65 degrees in H-plane and elevationangle better than 70 degrees in E-plane respectively whichis extended in horizontal direction significantly
4 Conclusion
In this paper a new method to improve the fidelity factorof a planar Vivaldi UWB antenna has been proposed Twodielectric slabs which play the role of a spatial filter suitableto restore the signal waveform in time domain are added tothe original Vivaldi antenna By tuning the dimensions andthe relative position of the dielectric slabs the fidelity factorin the half space is optimized The angular available range inH-plane with the fidelity factor greater than the value of 09has been improved by 95 and the available angular range inE-plane has been improved by 14
Acknowledgments
The authors would like to express their sincere gratitude toCSTLtd Germany for providing a free package of CSTMWS
International Journal of Antennas and Propagation 7
softwareThis workwas supported in part by the key programof the National Natural Science Foundation of China underGrant 61032003 and the National Basic Research Program ofChina under Grant 2009CB320402
References
[1] Y Q Zhang Y X Guo and M S Leong ldquoA novel multilayerUWB antenna on LTCCrdquo IEEE Transactions on Antennas andPropagation vol 58 no 9 pp 3013ndash3019 2010
[2] T A Vu M Z Dooghabadi S Sudalaiyandi et al ldquoUWBVivaldi antenna for impulse radio beamformingrdquo inProceedingsof the 27th Norchip Conference pp 1ndash5 Trondeim NorwayNovember 2009
[3] E Pancera T Zwick and W Wiesbeck ldquoSpherical fidelitypatterns of UWB antennasrdquo IEEE Transactions on Antennas andPropagation vol 59 no 6 pp 2111ndash2119 2011
[4] F Gross Frontiers in Antennas Next Generation Design ampEngineering McGraw-Hill 2011
[5] G Cappelletti D Caratelli R Cicchetti and M SimeonildquoA low profile printed drop-shaped dipole antenna for wide-band wireless applicationsrdquo IEEE Transactions on Antennas andPropagation vol 59 no 10 pp 3526ndash3535 2011
[6] A A Gheethan and D E Anagnostou ldquoDual band-reject UWBantenna with sharp rejection of narrow and closely-spacedbandsrdquo IEEETransactions onAntennas and Propagation vol 60no 4 pp 2071ndash2076 2012
[7] L Desrumaux A Godard M Lalande V Bertrand J Andrieuand B Jecko ldquoAn original antenna for transient high powerUWB arrays the Shark antennardquo IEEE Transactions on Anten-nas and Propagation vol 58 no 8 pp 2515ndash2522 2010
[8] L R LewisM Fassett and J Hunt ldquoA broadband stripline arrayelementrdquo in Proceedings of the IEEE Antennas and PropagationSymposium Digest pp 335ndash337 Atlanta Ga USA 1974
[9] Y Li and A Chen ldquoDesign and application of Vivaldi antennaarrayrdquo in Proceedings of the 8th International Symposium onAntennas Propagation andEMTheory (ISAPE rsquo08) pp 267ndash270Kunming China November 2008
[10] A Z Hood T Karacolak and E Topsakal ldquoA small antipodalvivaldi antenna for ultrawide-band applicationsrdquo IEEE Anten-nas and Wireless Propagation Letters vol 7 pp 656ndash660 2008
[11] J Bai S Shi and D W Prather ldquoUltra-wideband slot-loaded antipodal Vivaldi antenna arrayrdquo in Proceedings of theIEEE International Symposium on Antennas and Propagation(APSURSI rsquo11) pp 79ndash81 Spokane Wash USA 2011
[12] J Zhang J Wang and W Hu ldquoAnalysis of UWB signal distor-tion in transmittingreceiving antenna systemsrdquo in Proceedingsof the 9th International Symposium on Antennas Propagationand EM Theory (ISAPE rsquo10) pp 163ndash166 Guangzhou ChinaDecember 2010
[13] K Trott B Cummings R Cavener M Deluca J Biondi andT Sikina ldquoWideband phased array radiatorrdquo in Proceedings ofthe IEEE International Symposium on Phased Array Systems ampTechnology pp 383ndash386 Boston Mass USA October 2003
[14] D Carsenat and C Decroze ldquoUWB antennas beamformingusing passive time-reversal devicerdquo IEEE Antennas andWirelessPropagation Letters vol 11 pp 779ndash782 2012
[15] M A Elmansouri andD S Filipovic ldquoPulse distortion andmit-igation thereof in spiral antenna-based UWB communicationsystemsrdquo IEEE Antennas and Wireless Propagation Letters vol59 no 10 pp 3863ndash3871 2011
[16] G Quintero J F Zurcher and A K Skrivervik ldquoSystem fidelityfactor a new method for comparing UWB antennasrdquo IEEETransactions on Antennas and Propagation vol 59 no 7 pp2502ndash2512 2011
[17] E Pancera and W Wiesbeck ldquoFidelity based optimization ofUWB antenna-radiation for medical applicationsrdquo in Proceed-ings of the IEEE International Symposium on Antennas andPropagation (APSURSI rsquo11) p 2411 Spokane Wash USA July2011
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of
6 International Journal of Antennas and Propagation
0010203040506070809
1
Improved antennaOriginal antenna
Fide
lity
fact
or in
H-p
lane
minus90 minus70 minus50 minus30 3010minus10 50 70 90120579 (deg)
(a)
0
010203040506070809
1
Fide
lity
fact
or in
E-p
lane
120579 (deg)
Improved antennaOriginal antenna
minus90 minus70 minus50 minus30 3010minus10 50 70 90
(b)
Figure 11 (a) Measurement results of fidelity factor in H-plane and(b) measurement results of fidelity factor in E-plane
Table 3 The geometrical parameters of the dielectric slabs
Parameter Value Unit119905 44 mm119882119904
40 mm1198713
43 mm119889 915 mm119871119904
70 mm
The prototypes of the two considered antennas are shownin Figure 8 while the numerical and measurement resultsconcerning the frequency behavior of the parameter |119878
11| of
the new antenna are reported in Figure 9The measurement of fidelity factor was carried out in
an enclosed anechoic chamber The measured antenna isinstalled on a rotating platform A wideband probe is used
Table 4 Fidelity factor of the improved antenna computed in E-plane and H-plane
H-plane (120593 = 90) E-plane (120593 = 0)120579 (degree) Fidelity factor 120579 (degree) Fidelity factor0 1 0 15 099995 5 09999510 098976 10 09997315 098881 15 09988820 098655 20 09970925 098285 25 09942130 097808 30 09902335 097300 35 09852140 097008 40 09790745 096478 45 09718650 095924 50 09650455 095839 55 09613760 095966 60 09624465 093783 65 09656670 086216 70 09615675 071946 75 09335180 049866 80 08640485 027054 85 074927
to receive the transient signal radiated by the antenna undertest when changing the azimuth and the elevation angle ofthe antennaThe fidelity factors calculated in the upper half-plane are plotted in Figure 10Themeasurement results of thefidelity factor in E-plane and H-plane are shown in Figure 11
The original Vivaldi antenna shows its good fidelity factorcharacteristics in a side-ways H-shape area with azimuthangle scanning less than 35 degrees in H-plane and elevationangle less than 65 degrees in E-plane respectively Theimproved Vivaldi antenna shows its good fidelity factorcharacteristics in a cross-shape area with azimuth anglescanning better than 65 degrees in H-plane and elevationangle better than 70 degrees in E-plane respectively whichis extended in horizontal direction significantly
4 Conclusion
In this paper a new method to improve the fidelity factorof a planar Vivaldi UWB antenna has been proposed Twodielectric slabs which play the role of a spatial filter suitableto restore the signal waveform in time domain are added tothe original Vivaldi antenna By tuning the dimensions andthe relative position of the dielectric slabs the fidelity factorin the half space is optimized The angular available range inH-plane with the fidelity factor greater than the value of 09has been improved by 95 and the available angular range inE-plane has been improved by 14
Acknowledgments
The authors would like to express their sincere gratitude toCSTLtd Germany for providing a free package of CSTMWS
International Journal of Antennas and Propagation 7
softwareThis workwas supported in part by the key programof the National Natural Science Foundation of China underGrant 61032003 and the National Basic Research Program ofChina under Grant 2009CB320402
References
[1] Y Q Zhang Y X Guo and M S Leong ldquoA novel multilayerUWB antenna on LTCCrdquo IEEE Transactions on Antennas andPropagation vol 58 no 9 pp 3013ndash3019 2010
[2] T A Vu M Z Dooghabadi S Sudalaiyandi et al ldquoUWBVivaldi antenna for impulse radio beamformingrdquo inProceedingsof the 27th Norchip Conference pp 1ndash5 Trondeim NorwayNovember 2009
[3] E Pancera T Zwick and W Wiesbeck ldquoSpherical fidelitypatterns of UWB antennasrdquo IEEE Transactions on Antennas andPropagation vol 59 no 6 pp 2111ndash2119 2011
[4] F Gross Frontiers in Antennas Next Generation Design ampEngineering McGraw-Hill 2011
[5] G Cappelletti D Caratelli R Cicchetti and M SimeonildquoA low profile printed drop-shaped dipole antenna for wide-band wireless applicationsrdquo IEEE Transactions on Antennas andPropagation vol 59 no 10 pp 3526ndash3535 2011
[6] A A Gheethan and D E Anagnostou ldquoDual band-reject UWBantenna with sharp rejection of narrow and closely-spacedbandsrdquo IEEETransactions onAntennas and Propagation vol 60no 4 pp 2071ndash2076 2012
[7] L Desrumaux A Godard M Lalande V Bertrand J Andrieuand B Jecko ldquoAn original antenna for transient high powerUWB arrays the Shark antennardquo IEEE Transactions on Anten-nas and Propagation vol 58 no 8 pp 2515ndash2522 2010
[8] L R LewisM Fassett and J Hunt ldquoA broadband stripline arrayelementrdquo in Proceedings of the IEEE Antennas and PropagationSymposium Digest pp 335ndash337 Atlanta Ga USA 1974
[9] Y Li and A Chen ldquoDesign and application of Vivaldi antennaarrayrdquo in Proceedings of the 8th International Symposium onAntennas Propagation andEMTheory (ISAPE rsquo08) pp 267ndash270Kunming China November 2008
[10] A Z Hood T Karacolak and E Topsakal ldquoA small antipodalvivaldi antenna for ultrawide-band applicationsrdquo IEEE Anten-nas and Wireless Propagation Letters vol 7 pp 656ndash660 2008
[11] J Bai S Shi and D W Prather ldquoUltra-wideband slot-loaded antipodal Vivaldi antenna arrayrdquo in Proceedings of theIEEE International Symposium on Antennas and Propagation(APSURSI rsquo11) pp 79ndash81 Spokane Wash USA 2011
[12] J Zhang J Wang and W Hu ldquoAnalysis of UWB signal distor-tion in transmittingreceiving antenna systemsrdquo in Proceedingsof the 9th International Symposium on Antennas Propagationand EM Theory (ISAPE rsquo10) pp 163ndash166 Guangzhou ChinaDecember 2010
[13] K Trott B Cummings R Cavener M Deluca J Biondi andT Sikina ldquoWideband phased array radiatorrdquo in Proceedings ofthe IEEE International Symposium on Phased Array Systems ampTechnology pp 383ndash386 Boston Mass USA October 2003
[14] D Carsenat and C Decroze ldquoUWB antennas beamformingusing passive time-reversal devicerdquo IEEE Antennas andWirelessPropagation Letters vol 11 pp 779ndash782 2012
[15] M A Elmansouri andD S Filipovic ldquoPulse distortion andmit-igation thereof in spiral antenna-based UWB communicationsystemsrdquo IEEE Antennas and Wireless Propagation Letters vol59 no 10 pp 3863ndash3871 2011
[16] G Quintero J F Zurcher and A K Skrivervik ldquoSystem fidelityfactor a new method for comparing UWB antennasrdquo IEEETransactions on Antennas and Propagation vol 59 no 7 pp2502ndash2512 2011
[17] E Pancera and W Wiesbeck ldquoFidelity based optimization ofUWB antenna-radiation for medical applicationsrdquo in Proceed-ings of the IEEE International Symposium on Antennas andPropagation (APSURSI rsquo11) p 2411 Spokane Wash USA July2011
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of
International Journal of Antennas and Propagation 7
softwareThis workwas supported in part by the key programof the National Natural Science Foundation of China underGrant 61032003 and the National Basic Research Program ofChina under Grant 2009CB320402
References
[1] Y Q Zhang Y X Guo and M S Leong ldquoA novel multilayerUWB antenna on LTCCrdquo IEEE Transactions on Antennas andPropagation vol 58 no 9 pp 3013ndash3019 2010
[2] T A Vu M Z Dooghabadi S Sudalaiyandi et al ldquoUWBVivaldi antenna for impulse radio beamformingrdquo inProceedingsof the 27th Norchip Conference pp 1ndash5 Trondeim NorwayNovember 2009
[3] E Pancera T Zwick and W Wiesbeck ldquoSpherical fidelitypatterns of UWB antennasrdquo IEEE Transactions on Antennas andPropagation vol 59 no 6 pp 2111ndash2119 2011
[4] F Gross Frontiers in Antennas Next Generation Design ampEngineering McGraw-Hill 2011
[5] G Cappelletti D Caratelli R Cicchetti and M SimeonildquoA low profile printed drop-shaped dipole antenna for wide-band wireless applicationsrdquo IEEE Transactions on Antennas andPropagation vol 59 no 10 pp 3526ndash3535 2011
[6] A A Gheethan and D E Anagnostou ldquoDual band-reject UWBantenna with sharp rejection of narrow and closely-spacedbandsrdquo IEEETransactions onAntennas and Propagation vol 60no 4 pp 2071ndash2076 2012
[7] L Desrumaux A Godard M Lalande V Bertrand J Andrieuand B Jecko ldquoAn original antenna for transient high powerUWB arrays the Shark antennardquo IEEE Transactions on Anten-nas and Propagation vol 58 no 8 pp 2515ndash2522 2010
[8] L R LewisM Fassett and J Hunt ldquoA broadband stripline arrayelementrdquo in Proceedings of the IEEE Antennas and PropagationSymposium Digest pp 335ndash337 Atlanta Ga USA 1974
[9] Y Li and A Chen ldquoDesign and application of Vivaldi antennaarrayrdquo in Proceedings of the 8th International Symposium onAntennas Propagation andEMTheory (ISAPE rsquo08) pp 267ndash270Kunming China November 2008
[10] A Z Hood T Karacolak and E Topsakal ldquoA small antipodalvivaldi antenna for ultrawide-band applicationsrdquo IEEE Anten-nas and Wireless Propagation Letters vol 7 pp 656ndash660 2008
[11] J Bai S Shi and D W Prather ldquoUltra-wideband slot-loaded antipodal Vivaldi antenna arrayrdquo in Proceedings of theIEEE International Symposium on Antennas and Propagation(APSURSI rsquo11) pp 79ndash81 Spokane Wash USA 2011
[12] J Zhang J Wang and W Hu ldquoAnalysis of UWB signal distor-tion in transmittingreceiving antenna systemsrdquo in Proceedingsof the 9th International Symposium on Antennas Propagationand EM Theory (ISAPE rsquo10) pp 163ndash166 Guangzhou ChinaDecember 2010
[13] K Trott B Cummings R Cavener M Deluca J Biondi andT Sikina ldquoWideband phased array radiatorrdquo in Proceedings ofthe IEEE International Symposium on Phased Array Systems ampTechnology pp 383ndash386 Boston Mass USA October 2003
[14] D Carsenat and C Decroze ldquoUWB antennas beamformingusing passive time-reversal devicerdquo IEEE Antennas andWirelessPropagation Letters vol 11 pp 779ndash782 2012
[15] M A Elmansouri andD S Filipovic ldquoPulse distortion andmit-igation thereof in spiral antenna-based UWB communicationsystemsrdquo IEEE Antennas and Wireless Propagation Letters vol59 no 10 pp 3863ndash3871 2011
[16] G Quintero J F Zurcher and A K Skrivervik ldquoSystem fidelityfactor a new method for comparing UWB antennasrdquo IEEETransactions on Antennas and Propagation vol 59 no 7 pp2502ndash2512 2011
[17] E Pancera and W Wiesbeck ldquoFidelity based optimization ofUWB antenna-radiation for medical applicationsrdquo in Proceed-ings of the IEEE International Symposium on Antennas andPropagation (APSURSI rsquo11) p 2411 Spokane Wash USA July2011
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of