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CHAPTER 2 Literature Review

Printed microstrip radiators were first proposed as early as 1953, the first actual MSA

appeared in 1974, more than 20 years after the original suggestion was made. Last

couple of years MSA’s became popular because of its applications in communication

systems with miniaturizations and reduction in cost. There is tremendous development

and advancement in MSA field, so obviously it is necessary to take review to address

the new development in antennas and MSAs. For designing MSAs there are many

CAD tools CAD tools are available in the market which gives lot of flexibility while

designing MSAs. Literature on MSAs is available in publications. It includes number

of books, manuals. This covers latest developments occurred time to time. Fabrication

process of MSAs is similar to that of electronic circuit PCB fabrication. MSAs can

be fabricated using PCB technology, because of this mass production is possible at a

moderate cost. There are several advantages of MSAs which includes easy fabrication,

lightweight, low cost and small-volume. Also they can be made compact with the host

surface. These antennas are used in defence. Use of MSAs is becoming popular even

in commercial applications. Thus MSAs are replacing conventional antennas.Narrow

34

Chapter 2. Literature Review

bandwidth is main disadvantage of MSAs therefore bandwidth enhancement is main

aim of many researchers. However, it is observed that, primary goal of many researches

is towards gain enhancement and bandwidth enhancement. This observation is based

on review of many research papers published in journals. To understand the funda-

mental concepts literature review starts with books, research publications, laboratory

manuals of hardware and software design tools and measurement systems. This chap-

ter gives the idea about findings previous research work carried out by researchers

followed by important observations with respect to subject of interest related with the

work presented in this thesis.

2.1 Previous Research Work

Wireless Communication: Principles and Practice a book written by Rappaport [1]

gives basic concepts of communication, types of communication, block diagram and

working , overview communication systems, satellite, mobile communication with uplink

and downlink, frequency allocation and frequency spectrum of communication (EM) ,

mobile communication concept and principle, mobile communication frequency allocation,

mobile communication overview, mobile to mobile communication link, cell structure,

1G,2G,3G mobile systems.

Constantine A. Balanis [2] in his book, Antenna Theory Analysis and Design

presents antenna basic principle, equivalent structure of antenna, antenna as a tran-

sition device, types of antenna, radiation mechanism of antenna, radiation pattern

antenna, basic parameters of antenna, basic principle of MSA, rectangular MSA, cir-

cular MSA, beginning with primary parameters and secondary parameters of antenna

design, parameters of antenna like return loss VSWR, radiation pattern antenna gain,

directivity, bandwidth, detail study of antenna. Design equations of rectangular MSA,

JJT University 35


circular MSA and overview of various performance parameters of antenna. These

parameters includes bandwidth of antenna, loss due to reflection, standing wave ratio,

directivity and radiation pattern, antenna gain, are elaborated.

Recent trends in MSA technology is highlighted by Hanumantha Rao Patnam [3].It

is shown that, use of reflect array antennas and reconfigurable antennas improves the

bandwidth. This has been achieved using electromagnetic band gap structures. Var-

ious algorithms like frequency selective surfaces, GA are used for antenna designs.

Techniques for Improvement in the bandwidth is included in review. Smart antennas,

EBGs, FSS, reconfigurable antennas and GA developments based designs have been

presented in past.

Several designs for small-size wide-bandwidth MSA are examined through simulation

and experiment by Aaron K. Shackelford et al [4]. By increasing dielectric constant

od substrate material several techniques are used to reduce the resonant length of wide

MSAs. In this paper L-probe-fed patch and U-slot patch wide band antennas are

presented. Here by adding shorting wall and shorting upper conducting patch and ground

plane, the simulation and experimentation is carried out. Results and analysis of this

paper gives conformation that as antenna size reduced by 94% and it maintains excess 20

% impendence bandwidth.

Amit A. Deshmukh and K. P. Ray [5] this paper elaborates broadband rectangular

MSA, using cutting a half-U-slot. This also includes effect of rectangular slot on patch

edges. Proposed work presented here clears that compact and broadband rectangular

MSAs generated by cutting a slot of shape half-U-slot or rectangular,inside the patch.

Here it is observed that Antenna bandwidth increases as compared to rectangular JJT University 36


slot by using two resonant slots. If we comparison of single half-U-slot-cut BW with

rectangular slot using RMSA shows that, the RMSA has 50% enhancement. • Gain • Input impedance • Radiation pattern.

The gain of MSA is more than 7dBi over the entire BW with the broadside radiation

pattern.

Hang Wong, Kwai et al [6] presented antennas for wireless applications with compact

size and wider bandwidth. Various antennas like monopole, loop, and dipole MSA sizes

are reduced by using various designs are studied and presented, reviewed to that of

several popular generic antennas. Two enhancement of bandwidth of MSA, various

principles and concepts of operation of these antennas have been discussed. Therefore

different VAD tools available in market and study to design effective antenna have

been presented in this paper.

Mayuri. M. Dekate [7] presented a circularly polarized MSA which can be realized

by exciting two orthogonal modes with equal magnitudes in LTE band II for 4G MIMO

with frequencies of 1860 MHz-1910 MHz which is uplink frequency and 1930 MHz-1990

MHz which is downlink frequency. So the antenna is dual band antenna. The center

frequency for first band is 1880 MHz and desired bandwidth is of 60 MHz. The center

frequency for second band is 1960 MHz and desired bandwidth is 60 MHz. Center

frequencies of 1920 MHz is considered for the designing of antenna which is mean of

1880 MHz and 1960 MHz JJT University 37


In this paper comparison of RF simulations using HFSS and CST Microwave software, for

a commercially available 7T multi-channel coil is presented by M. Kozlov and R. Turner

[8]. Here simulation parameters for example size are selected and fully coverage of the

results is ensured. There is agreement between simulated and measured S parameters,

between simulated and actual values and between simulated and measured RF simulation

field. Here author investigated the influencing precision conditions and simulation time.

Therefore both simulation methods presented in this paper provides comparable results

within 15 % in implementations. Ansoft HFSS frequency domain simulation solver much

faster than the CST time domain solver.

Design rules of MSA with polarization reconfigurable features, right-handed circular

polarization described by Hakim Aissat et al [9]. It also describes left-handed cir-

cular polarization. Using diagonal slot along with CPW open end excitation, the basic

circular CPW-fed MSA is studied. Results of simulation are compared with measured

results and it is observed for the passive version of the antenna excited by an asym-

metric slot. Beam-lead pin diodes were used in reconfigurable antenna and this was

used to polarization along with electrical modelling of the diodes. Also, discussion on

efficiency reduction resulting from the diode losses is carried out in this paper.

Design formulas presented by Yue Ping Zhang [10] to determine dimensions of the

patch. It also includes formulas for feed point location in case of single-ended MSA.

Observations shows that patch length can be determined using formulas. These for-

mulas are used for the frequency concerned with requirement. the formula is used to

calculate width of patch. This ensures the excitation using the probe feed techniques

for fundamental mode . Here is given that the condition which links the width of

patch the point of probes feed location, and excitation of the fundamental mode. Per-

formance evaluation of the wider band techniques was carried out for single-ended , JJT University 38


differentially-driven MSA. Impedance bandwidth improvement is proposed for H slot

differentially-driven MSAs in this paper.

Under resonance conditions, a MSA designed by Hussen Attia and Leila Yousefi [11]

to achieve the highest possible gain. The resonance conditions for high gain MSAs covered

with substrate is derived using transmission line analogy and the cavity model of a patch

antenna. High gain can be achieved with substrate having very high permeability, under

resonance conditions. The analytical formulation for the antenna far fields was verified

using numerical methods is elaborated in this paper.

Impedances analysis, in case of differential feed RMSAs was presented by Ziqiang

Tong et. al[12] It is observed that the impedance of a above antenna exhibits cosine

squared behaviour over the feed distance. Calculations of the impedance match feed

positions improved expressions for this RMSAs with given dimensions is explained.

Here two antenna prototypes are designed and proved using simulation and measurement

results, which match the theoretical analysis.

Enhancement of bandwidth of MSAs is demonstrated by Jia-Yi Sze [13]. by loading of

a pair of right-angle and a U-shaped slot in a RMSAs. Good radiating characteristics

with bandwidth enhancement have been determined experimentally with desired

dimensions. this was both for rightangle or U-shaped slot. This study shows that the

bandwidth of designed antenna can be enhanced by factor about 2.4 as compared to that

of a unslotted RMSA.

For UWB planar monopole antenna by D. N. Elsheakh et al [14]. Presented a com-

pact design . Achieving the UWB operation based on circular microstrip monopole

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antenna was discussed in this paper. results shows that discontinuities in bandwidth

ranging from 3 to 35 GHz , 7 to 10 GHz, 12.5 to 17.5 GHz. Size of the antenna is

reduesd by about 27 % of a conventional RMSA. Also antenna performance can be

improved using EBG structures. In circular and square patches metallo-EBG structure

(MEBG) MSAs, it is possible to remove ripples in the operating band and it is possible

to reduce antenna size by more than 60 % as to regular patch antennas. This design

provides an impedance bandwidth of more than 33 GHz and averaged radiation efficiency

up to 74 % ,and gain of 6.5 dB.

The design and analysis of a coplanar capacitive fed MSA suspended above the ground

plane is presented by Veeresh G. Kasabegoudar et al [15]. Good gain 50 %

impendence bandwidth approach is proposed and demonstrated in this paper while

designing antennas in various operating microwave bands. Coaxial probe capacitive

feed strip feed Antenna model using equivalent circuit approach is incorporated. Here

results are matched by simulated and practical results. The capacitive feed strip used.

And in this, basically a RMSA capacitor is formed from a truncated microstrip

transmission line. The error analysis was carried out for varification of the model for

different design parameters. The antenna configuration can be used where directional

radiation patterns are required over a wider bandwidth.

Rectangular dielectric resonator in combination with a grounded, inverted L-plate

wide-band compact antennas proposed by Kang Lan et al [16]. Two different

impedance matching circuits were compared. In first, one side of the dielectric res-

onator is attached with vertical T-shaped strip. In second, microstrip stub terminated.

This was terminated into a T-branch. Impedance matching is achieved using circuits

to enhance the matching. This results in saving the space utilization. Design of the JJT University 40


radiation element, feed structure of the antenna is carried out using a two-step procedure.

Antenna dimensions are achieved using approximate formulas to obtain initial

estimation. Finite-difference time-domain method was used to obtained desired operating

frequency and quality factor. In this fast FFT method is used for fine-tuning. Desired

value of impedance matching is achieved using proper feed structure by .designing and

adjusting the feed location. Best performances and optimized design is generated by

designing the radiating element and the feed structure separately. As an example two

antennas are designed at 2.4-5.8 GHz Bluetooth and wireless local-area network

applications. The 10 dB bandwidths between 210 - 240 MHz are obtained. The antenna

gains are 1.0 and 1.5 dB, respectively.

A coaxial-fed rectangular dielectric resonator antenna loaded by a folded metallic patch is

studied by K. Y. Hui et al [17]. Amongst the metallic patch and the dielectric

resonator foam layer is introduced , there for the impedance BW for the antennas

increased from 2.2 to 6.3 % (10-dB BW). The antenna has a maximum gain of 5 dB.

Observed simulation and measurement results are best.

Square MSA with 4 slits and a pair of truncated corners with compact circular-

polarization operation is proposed and investigated by Wen-Shyang Chen et al [18].

Compact CP design at given resonance frequency it is observed through experimental

results that reduction in size by around 36 % as compared to normal corner truncated

R MSA. Size of the truncated corners for CP operation is much More than size of the

normal CP design. using a RMSA. This allows tolerance in manufacturing for the pro-

posed design. Detail study of experimental results and simulated results are presented.

Attractive feed for the 10 % thickness of the resonant wavelength MSA with L-shaped

probe is shown and a parametric study on RMSA is presented by C. L. Mak et al [19].

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7db gain and 36 % impedance bandwidth, gain bandwidth is found for the MSA,a two-

element array fed by L-probes is also discussed. proposed antenna design can suppress

the cross polarization radiation. across the pass band both the antennas gives stable

radiation patterns. L-probe does not have much effect on resonant frequencies of the

proposed antenna. Antenna design using existing formula and the resonant frequency

results in agreed values.

Printed wide-slot antennas with E patch and slots, for wireless applications, are pro-

posed by AliakbarDastranj et al [20]. They are fed by a coplanar waveguide and

a feed line with almost the same performances. Here detail simulation and measured

results using design in simulation and practically measured analysis are conducted to

understand their behaviours and optimize for broadband operation. It is observed that

perfect marching of results between experimentally and simulation has been achieved.

The impedance bandwidths, determined by 10-dB reflection coefficient, of the proposed

slot antennas fed by microstrip line and CPW, from both measurement and simula-

tion, are about 136 % and 146 % respectively. This large operating BW is obtained

by choosing suitable combinations of feed and slot shapes. In order to achieve wider

operation bandwidth both of the designed antennas have round corners on the wide

slot and patch. These antennas results multi directional radiation patterns, along with

higher gain, and reduces cross polarization radiation pattern . Radiations in far-field E

and H-plane was studied in this paper work and shows that reflection coefficient , gain

can be achieved by the design. Analysis was carried out for comprehensive numerical

sensitivity to understand the role of different dimensional parameters used to optimize

the performance

By generating U-shaped slot in copper patch single-layer coaxially fed rectangular

MSA is designed to operate at a wide operating bandwidth. Impedance bandwidths JJT University 42


of 10 % - 40 %,is achieved even with nonair substrates while designing this type of

antenna structure experimentally. Steven Weigand et al [21] developed through exam-

ination of the structures, principle design procedures for multiple resonant frequencies

, the radiation and impedance properties for various antenna geometries. Results of

Simulations, experimental measurements of these antennas designed are presented and

discussed for further study, the design rules are derived by analysis of former experi-

ments and method of moments (MoM), simulation results approximation.

Compact open-slot antenna for BW enhancement is presented by WeiXing Liu et

al[22]. Asymmetrical rectangular patch with the U-shaped open-slot structure is gen-

erated by using multiple resonances; impedance matching is achieved by cutting two

bevels on the patch to improve. The proposed antenna provides a wide impedance

bandwidth of 122 % with 10-dB return loss. It is shown that the impedance BW can

be enhanced from 28 to 122 % by using different antenna types. Moreover, this slot

antenna is with a small size of mm, while maintaining the ultra-wideband performance.

A design of circular polarization MSA with equilateral-triangular single-feed and gain

of antenna is enhanced and this is presented by Jieh-SenKuo et al[23]. In this

method three slots of triangular shape are generated at locations below the triangular

radiating patch .This location is in the ground plane to design and obtain the CP.

one of the triangular slots is adjusted to that of lengths of side slightly greater. Two

resonant modes for CP, orthogonal radiation may be excited. Measurement of antenna

gain is carried out here .It is seen that gain is easily increased by 3.3 dB. This is as

compared to the same height. similarly substrate material and resonant frequency,

affects radiating patch shape for a triangular MSA even without triangular slots in

the ground. Results observed by experimentation, and simulation are compared and JJT University 43


discussed in this paper.

Designs of single-feed for circular polarization, equilateral-triangular MSAs are

discussed in this paper and this is studied experimentally by Jui-Han Lu et al [24]. It

is demonstrated that circularly polarized radiation of MSAs can easily be achieved using

a one probe feed by integrating a narrow or a cross slot of unequal lengths in the

triangular patch. Here results shows that for cross slot, the proposed antenna can

perform CP to reduce size of antenna at a given operating frequency. This results

smaller size for the proposed antenna for performing CP radiation as compared to a

normal CP triangular MSA at a given operating frequency.

Folded shorting wall in broadband triangular shaped patch antenna has been proposed

and explained by Yuan Li et al [25]. Modified patch shape is proposed by studding

the effect of the folded shorting wall. 6.4 dBi gain is found, stable, over a bandwidth

of 28.1 %. By comparing the conventional or regular rectangular patch antenna it is

observed that it exhibits 48 % size reduction, and enhancement in BW by 34 %

Use of a cylindrical Electromagnetic Band gap substrate the performance of a cir-

cular MSA is improved demonstrated by Halim Boutayeb et al [26]. in this pa-

per. A cylindrical electromagnetic band gap substrate performance of the MSA with

mushroom-shape substrate and coaxial probe feeding .This results increase antenna

gain. Combination of two periodic structures, the cylindrical electromagnetic band

gap with different periods. This was achieved as One made of metallic rings and the

second of grounding. Circular and radial periodic structure was form by disposing of

a radially and circularly periodic structure. Analysis based on parameters was done

using a full-wave method. This was carried out to design the EBG structure. Us-

ing proposed concept design of the antenna is carried out and tested, which results

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good radiation patterns. Also performances parameters like return loss is in standard

acceptable level obtained from measurements. Also results show a good impedance

matching and a gain enhancement of the proposed antenna.

A tunable Meta material in IC structures is investigated through an example of a

MSA on a mushroom-type EBG structure by Jing Liang et al [27]. The MSA is

designed as a 1/2-wavelength resonator of an EBG loaded microstrip transmission line

at the operating frequency of a MSA can be switched and controlled dynamically by

loading diode switches in between vias and the ground plane. When the EBG surface

is ground shorted, then the switches are on that is ON state. When the EBG surface

is dc open that means switches are OFF that is OFF-state. Antenna resulting patch

in-band operating frequencies at ON and OFF states are found very different. Dual

band frequencies, gain and efficiency for antenna are observed along with radiation

patterns. This switchable EBG-patch antenna is designed and fabricated. This was

tested in these two states. The results of measurement and simulation shows that

the results are best . The tuning of resonant frequency was done in case of selected

switches within the EBG element.

Circularly polarized ring antennas with single-feed method have been investigated by

Kin-Fai Tong et al [28]. Selection of input ports from one of the two ports of the

antennas are achieved and carried out either by right-handed or left-handed is investi-

gated in this paper. MSA ,with U-shaped, using feed line technique proposed work is

presented here by the fundamental mode of the ring radiating patch element. In this

proximity coupling along with semi-annular section was used. Induced rotating sur-

face was contributed by ring radiator currents on to the CP behaviour of the antennas,

here two types of rings are investigated and introduced. One square ring prototypes JJT University 45


operate at resonant frequency 2.7 GHz has been designed. Then fabrication and mea-

surements are evaluated to show the basic principles of the antennas. Second annular

ring radiating patch elements at resonant frequency 2.255 GHz are designed to realize,

to demonstrate the capability of the new feeding structure of antenna. In the design,

a high isolation RF which is used to direct the input signal between the two input

ports. The antenna is designed to radiate desired energy in circular polarization can

be easily at both types of circular polarization, by making suitable biasing arrange-

ment of RF switch. A single microstrip line feed is used in this reconfigurable design.

Various performance parameters of prototype antennas such as return losses, axial ra-

tios, gains and radiation patterns have been measured for validation and verification.

A parametric study of feeding structures with a square ring antenna has been carried

out for important design.

Circular MSAs with circularly polarized aperture-coupled feed are presented and

investigated by Nemai C. Karmakar et al [29] This shows an 8 % improvement in

impedance and bandwidth in L-band. Three varieties were used to obtained

performance of antenna .Individual and a stack of single-feed patch with perturbation

segments was compared with dual-feed patch having a 3-dB line coupler.It shows that

ellipticity bandwidth was observed in case of the single-feed stacked patch and the

dual-feed patch. This meets the requirements. In this research work use of low-cost

substrates and foam for bandwidth enhancements are attractive for various

applications, hence which results to observe importance of production cost. Above

three variety of micro strip antenna feature more than 9-dBi gain.

Printed wide-slot MSA with a fractal shaped slot using microstrip-line-fed for band-

width Improvement is proposed and studied by Wen-Ling Chen et al [30]. Oper-

ating bandwidth can be enhanced by fabricating the wide slot MSA as fractal shapes JJT University 46


and the relation between the bandwidth, the Iteration Order and Factor of the fractal

shapes is practically studied and verified. The proposed fractal slot MSA can achieve an

operating bandwidth of 2.4 GHz at frequencies around 4 GHz, which is about 3.5 times

that of a normal microstrip-line-fed printed wide-slot antenna. The results shows that the

impedance bandwidth, reflection coefficient, achieved a 2-dB gain with bandwidth of at

least 1.59 GHz.

For the performance in case of radiation field of a MSA loaded with a general su-

perstrate,a analytical solution is proposed. This is based on concept of reciprocity

theorem and uses the transmission line analogy. The cavity model of MSA is pro-

posed and demonstrated by Hussein Attia et al [31] analytical formulation was

given for the antennas far-field, which is faster than full-wave numerical methods. It

requires 2 % of the time as compared to the time that full-wave analysis acquires.

Design, optimization of the proposed method is thoroughly verified using numerical

and experimental results. Result verification was carried out for conventional dielec-

tric as well as artificial superstrates. The analytical formulation was extended in case

of a patch antenna which was integrated in a multilayered synthetic dielectric struc-

ture This technique was firstly implemented practically MSA working in the Universal

Mobile Telecommunications System band and covered with a superstreet made of an

artificial periodic metamaterial with dispersive permeability and permittivity

By removing partially substrate surrounding the patch to enhance gain of a MSA

technique is investigated is proposed by Siew Bee Yeap et al [32]. By removing

partial substrate it is possible to reduce the losses due to surface waves and dielectric

substrate. In this paper the study of gain of antenna is carried out numerically and

validated experimentally, by removal of substrate in different configurations. Here it

is observed that partial substrate removal gain can be enhance to that of conventional JJT University 47


patch antenna, e.g. up to 2.7 dB. Also, it is observed that the improvement of gain is

more due to loss reduction of surface waves and dielectric substrate than increase in

patch size when the effective dielectric constant of substrate is reduced.

Enhancement in Band-width of MSA line feeded, printed wide-slot antenna rotated

slot is proposed and experimentally studied by Jen-Yea Jan and Jia-Wei Su [33].

In this paper work presented is based on performance parameters such as gain charac-

teristics of this type of antenna, input impedance and radiation pattern. It is observed

from results of experimentation which are measured impedance band-width, as per

reference 10 dB return loss. Operating bandwidth of 2.2 GHz can be achieved at

resonant frequencies 4.5 GHz. This is four times better than that of a conventional

line feed , printed wide-slot MSA. Gain of antenna over operating band is measured

and compared and it is observed that achievement of 2 dB gain, at bandwidth of 1 GHz.

A way of improving the bandwidth of two different electromagnetically coupled MSAs

by use of a tuning stub proposed in a paper published by Sean M. Duffy [34].

Theory and equations are developed to demonstrate the potential BW improvement

and required stub impedance characteristics. A dual-stub design is presented, which

achieves better characteristics than a conventional quarter wavelength open-end stub.

A microstrip line feed with a fork-like tuning stub Printed wide-slot antennas for

bandwidth improvements are proposed and practically investigated by Jia-Yi Sze et al

[35]. Impedance characteristics along with radiation characteristics are studied.

Results shows achievement of 1:1.5 VSWR BW of 1 GHz is observed at frequencies

around 2 GHz. This is nearly 10 times better than that of a normal feed line wide slot

MSA. Also 2-dB gain is achieved for BW of 500 MHz. JJT University 48


MSAs harmonic suppression and the impedance matching are experimentally tested

by Y. J. Sung et al [36]. To achieve these requirements, one-dimensional photonic

band gap (PBG) two structures are used. i) Defected Ground Structure ii) Compact

Microstrip Resonant Cell Line feed are considered for these MSAs. Effective induc-

tance of the PBG structure controls the characteristic impedance of the line feed MSA,

because of the additional effective inductance of this structure. 50Ω microstrip lines

may be used to feed MSAs easily, at the resonant frequency. This is achieved without

using matching circuits. Second harmonic in case of the this antennas is reduced as

compared to that of a normal antenna. Results shows that these PBG structures are

effective in harmonic reduction.

By using alumina as substrate and by including a 3-stage pseudo morphic high,electron

mobility transistor amplifier which is integrated with a higher gain antenna in a 60

GHz active MSA design is presented and explained by Camilla Karnfelt et al [37].

Here antenna is generated by ribbon bonded to the substrate and amplifier has 18 dB

gain is defined. It is a array antenna with a simple radiating element etched pattern for

giving producibility at higher frequencies. Two antenna are designed,. First a single

array having directivity of 13.4 dB. losses are approximately 1-2 dB, and gains of about

12 and 13 dB, simplicity is achieved with this design. Measurements are performed on

amplifier, antenna and the integrated design separately.

To study of the input impedance, radiation properties of the differentially driven MSAs,

theory based on the improved cavity model antenna is presented and expanded by Y.

P. Zhang et al [38] The differentially-driven MSAs were designed and fabricated, and

performance of these MSAs were verified experimentally. Results indicated that

occurrence of resonance also depends on the ratio of the separation in case of differentially

driven MSAs, with dual feeds. JJT University 49


The paper presented by Guo-Min Yang et al [39] demonstrates that, self-biased

magnetic films, with annular ring MSAs, cascaded with a microstrip ring and a tuning

stub. It is used to generate, annular ring antenna and is realized. NiCo-ferrite films

were used to load an annular ring antenna on a available substrate which operates at

1.7 GHz. antenna designs with NiCo-ferrite films on one side, and both sides of the

substrate were analysed . A down shift of 2-71 MHz of the operating frequency was

noted in case of antennas with self-biased magnetic films which were working at 1.7

GHz. As compared with non-magnetic antenna, in this gain enhancement by 0.8 dB

was observed.

Dual-element MSAs closely placed on a finite-sized ground plane with an efficient mutual

coupling reduction for WLAN MIMO application at 5.8 GHz is presented by J. OuYang

et al [40] This results in higher isolation by a simple slot structure on the ground of the

MSAs. To achieve maximum isolation, the position, and dimensions of the slot can be

calculated. These results, greater than 40 dB isolation and can achieved between two

parallel MSAs with ground plane. In order to validate, different prototypes were

fabricated, and tested using IE3D software tool.

The design of a frequency agile MSA described by Sean Victor Hum et al [41] is

easily coupled with differential RF transmitter and receivers. In this, 3 pairs of varac-

tor diodes are integrated in this case, with the MSA, and tuning is carried out. Tuning

ratios of 2 is possible with this design. Intrinsically broadband nature of the differ-

ential feeding scheme makes this possible. For predicting the port characteristics, an

intuitive equivalent circuit for antenna is presented. Losses produced by the varactor

diodes are accurately predicted by these circuits. It also results in radiation efficiency

of the antenna. Equivalent circuits were used for first time to performance analysis of

JJT University 50


the effect on varactor diode losses. This has been carried for antennas. Validation is

done using full-wave simulations and practical measurements at 2-4 GHz range

In the article given by Kai-Fong Leetal [42] provides general information about

MSAs and comments on size reduction of antenna and its effect on antenna pattern

with respect to simulation results are also given. Important conclusion of this article

states that size reduction gives significant degradation in antenna pattern.

Girish Kumar and K. P. Ray [43] talks in detail about various broadband MSA

configurations in their book with titled broadband MSA. They explain concepts of

various broadband techniques, which provides examples without involving mathemat-

ical detail. Many theoretical simulations and parametric studies have been especially

carried out to provide physical insight into antennas. Analysis and design of normal

shaped antenna patches of various shapes are also given with three different dielectric

materials.

MSA Design Handbook written by Ramesh Garg et al [44] describes analytical

modelling and analysis of rectangular and circular microstrip antennas. Bandwidth of

various types of broadband MSA’s utilizing parasitic loading techniques are compared in

this handbook as function of volume occupied by the antenna.

Gagandeep Sharma et al [45] provide HFSS and MATLAB simulation and design

calculations of rectangular MSA’s. The return loss, VSWR, Directivity, gain, radiation

pattern are evaluated. While concluding the authors says rectangular patch antenna is

a more conventional approach for the implementation of a Wi-Fi application and it’s

a good choice to replace commercially available dipole antenna. Edge feed rectangular

JJT University 51

Chapter 2. Literature Review MSA proposed in this paper operates at frequency 2.4835 GHz.

Investigation of radiation efficiency in case of dielectric resonator antenna (DRA) along

with a MSA at Ka band was carried out by Qinghua Lai et al [46]. Using same

feeding networks at operating frequency around 35 GHz antenna design can be carried

out such as circular disk MSA and cylindrical DRA. Then comparison can be made.

Directivity / gain method was used for this comparison. Same method was used to

measure efficiency of both devices. Wheeler cap method, in which the losses in the

test system, feeding techniques were considered for calibration purposes. Best results

were observed using simulation, practically for these methods, while considering the

effect of sampling interval, cross-polarization in the D/G method. Radiation efficiency

of the DRA is observed to be is significantly higher than that of the MSA at millimetre

wave frequencies.

This paper gives information about RMSA where integral equation method is used to

calculate the operating frequencies of a RMSA is demonstrated by Weng Cho chew

et al [47] Accuracy is achieved while determining the resonant frequencies of a

rectangular patch using integral equation method. This method formulated is with

vector Fourier transforms which gives rise to a diagonal form of the Greens function in the

spectral domain. The paper shows that that the meeting of the edge singularity

condition is not essential because the edge condition in a boundary value problem is a

sufficient but not a necessary condition.

A Wiley publication book, Microstrip and Printed antennas written by Debatosh

Guha [48] gives fundamental description of modelling of MSAs. A wide variety of

re-configurability have been discussed in this book with emerging trends and directions

for research. The book covers range of fundamental concepts and the state-of-the-art

JJT University 52

Chapter 2. Literature Review developments in designing the MSAs.

D. Rakesh et al [49] provides performance evaluation of RMSA on different substrate

materials. They observed decrease in bandwidth and gain by changing the dielectric

constant of the substrate material. Another observation indicates that the directivity

reduces with increase in permittivity. The Return loss and VSWR observed by the

author shows that the theoretical values for their proposed model were valid

A simple design formulation proposed by Guha and Siddiqui [50]. for computing

precise operating frequencies of CMSAs with dielectric superstrates is elaborated here. It is

widely applicable to high dielectric constant and low dielectric constant superstrates as

tested with different practical results. This show the best matching with the present theory

compared with others.

Antennas used in mobile communications handsets where discussed in the paper pub-

lished by Rod B. Waterhouse et al [51]. This paper deals with patches of antennas

with bandwidths suitable for commercial digital cordless systems. A novel technique

which alleviates the structural problems of a shorted patch was also proposed in this

paper. It has been shown that shorted patches are very suited to applications were

antenna real estate is very limited, for example, for a mobile communications handset.

A technique for reducing the radiation and coupling by compensating the effect of the

substrate has been demonstrated by Marija M. Nikolic [52]. The MSA was printed

on a substrate in the classical manner. An array of shorting pins between the patch

and the ground is introduced and designed so that the inductive current sin the pins

cancel out the capacitive polarization currents. As a result, in a narrow frequency

JJT University 53

Chapter 2. Literature Review band, the antenna behaves as if there is no dielectric at all.

Sonali Jain and Prof. Rajesh Nema [53] gives review of circular microchip an-

tennas. MSA with high frequency and inset-fed dual frequency design of circular MSA

to study the performance, analysis of CMSA using glass epoxy substrate reviewed in

this paper. The operating frequency of CMSA is selected and used in this design,

that is called as resonant frequency of this CMSA. CMSA resonates at 1.58 GHz and

2.43 GHz. The application of this design is in wireless communication field such as in

WLAN.

Design and simulation of circular patch antenna to achieve best performance parame-

ters using a Fortran program was developed in microwave communication is presented

by B. J. Kwaha et al [54]. Design, analysis and fabrication of MSA for configu-

rations, different shapes as per desired requirements can be achieved by developing

program. So MSA can be flush mounted on spacecrafts and in microwave communi-

cation, telecommunication, security, medicine etc. Results obtained in this design are

best in agreement with those obtained from rectangular microstrip patch.

Ali A. Dheyab Al-Sajee [55] gives enhancement bandwidth of MSA using tapered

single slot. RMSA using tapered slot with probe feed technique is designed in this

proposed antenna to achieve bandwidth enhancement. This design is simulated with

microwave office 2008 software package. This method is used to result analysis at the

frequency band of (2 GHz - 3 GHz), when the location is changed and dimensions of

tapered slot. Results gives acceptable levels of VSWR (less than 2), return losses (RL)

(- 10 dB) and impedance bandwidth of (13.1 %) at the frequency band of (2.2921 GHz-

2.6063 GHz) of [2-3] GHz. JJT University 54


Illustration of design of a square patch MSA with serrated edges and an N-shaped slot

has been shown as an alternative solution to increase the narrow bandwidth of the

conventional MSA by Anshika Khanna and D. K. Srivastava[ 56]. The designed

antenna gives an impedance bandwidth of 43.48 % around the resonant frequency of

2.1 GHz and is applicable in Bluetooth, WLAN and Wi-MAX applications

simultaneously. IE3D Zeland simulation software has been used for the simulation of

the intended design.

Inderj Bahl et al [57] sowed Design of MSA Covered with a Dielectric Layer. The

effective dielectric constant can be calculated using the variation technique. Numeri-

cal results show that the effective dielectric constant of a microstrip feed line covered

with a thick sheet of high dielectric constant is drastically affected by the cover. The

effect is more pronounced for small values of W/h ratio. Numerical and experimental

results for the fractional change in the resonant frequency have been found to be in

good agreement.

Here 2 single-feed corner-truncated MSAs with Debye-modeled substrates are simu-

lated in Konstantinos P. Prokopidis and Theodoros D. Tsiboukis [58]. The

input impedance and reflection coefficient are calculated. This is compared with the

lossless case. It demonstrates the input impedance and slightly influenced in the op-

erating frequencies.

H. Matzner and S. Leavy [59] give simulation of simple MSA using Zeland IE3D.

Step by step experimentation has been suggested by the author to carry out

experimentation of simulation of MSA. This experimentation helps the researcher in

performing and analyzing simple MSA’s.

High Frequency Structure Simulator (HFSS) manual [60] gives overview an-

tenna design process. This operational manual provides step by step instructions with

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respect to GUI of the software while designing and simulation of MSA. Ansoft Desktop

GUI takes inputs related with proposed antenna to be design and provides output

parameters to correlate the expected values of various antenna parameters. It also

provides 3-D pictorial view of proposed antenna.

E-Shape MSA is proposed by Neenansha Jain et al [61]. The antenna design for

various substrate thickness and result are analyzed. At 12 GHz they verify and tested

result on IE3D Simulation tool. This shows that results of proposed design are more

effective for frequency range 1GHz-15GHz.

A Design of Swastika Shaped Wideband MSA for GSM/WLAN Application proposed

by Vivek Singh Rathor and Jai Prakash Saini [62] gives compact MSA at

operating frequency of 2.5 GHz. The radiating element of the proposed antenna

consists of Swastika symbol patch using dielectric substrate 4.2, loss tangent0.0012

and having the same substrate height 1.6 mm. The antenna size is very compact

(28.8mm × 37.2mm × 1.6mm) and covers 1.696 GHz to 2.646 GHz and can be used for

GSM and WLAN applications. Using IE3Dsoftware package of Zealand, the designed

antenna is simulated. simulation results indicates that the antenna can realize wide-

band characteristics having good impedance bandwidth of 43.758 % (V SW R ≤ 2) for

all resonant frequencies.

Rectangular MSA at 2GHZ on Different Dielectric Constant proposed by Maruf

Ahamed et al [63] presents the result for different dielectric constant values and

the result is performed by thickness of 2.88mm and resonance frequency of 2GHz. A

Through analysis of the problem starts with the application of the equivalence princi-

ple which introduces the unknown electric and magnetic surface current densities on JJT University 56


the dielectric surface.

Radiation pattern and performance analysis of rectangular microstrip feed patch

antenna published by Khushbu Ahirwar et al [64] compares various antenna designs

using IE3D an electromagnetic simulation package by Zeland Software Inc. They have

compared the results of the design in the frequency band 2GHz to 3.5GHz and the best

configuration of antenna with suitable Return Loss(RL),VSWR, Bandwidth, Gain, 2D

and 3D Radiation Pattern has been suggested that can be used in practice for

communication purpose especially for mobile communication.

Bandwidth improvement of rectangular microstrip patch antenna by varying substrate

thickness presented by Paritosh Kumar et al [65] analyses that by using different

shape, feeding techniques and increasing the substrate thickness one can achieve mod-

ified bandwidth. The antenna band width is increased up to 25.10 % and it resonates

at 2.546 GHz resonance frequency. Along with band width antenna directivity, effi-

ciency and radiation pattern also changes the proposed antenna has high bandwidth

which can be used for wireless communication of high data rate. Compared with nor-

mal rectangular patch antenna with thickness2.4mm bandwidth obtained is 25.10 %.

While in antenna with thickness 1.2 mm and 1.6 mm the bandwidth obtained is18.20

% and 20.49 % respectively.

Verma Alka [66] gives analysis and design of circular MSA. Here design and analysis

of circular MSA in X band is carried out and studied. The operating frequency for

CMSA design is selected 9.8 GHz. Calculation for the various performance parameters

of CMSA are, propagation constant, effective radius and patch radius of the antenna,

with impedance matched to 50Ω using coaxial feed. The return loss and VSWR are

seen to standard values also performance observed using radiation pattern. MATLAB

JJT University 57


is used to design antenna and then IE3D software is used for verification and

confirmation of the design results.

Comparisons of Circular and Rectangular MSAs are given by T. Durag Prasad et al

[67]. Directivity of circular patch antenna is observed larger to that of rectangular

Patch antenna, where antenna design parameters used are same for both. In this paper

theory and simulation of both CMSA and RMSA is explained with respective design

and results. It is proved that Circular MSA is better when compared to that of

rectangular patch antenna.

Shing Lung Steven Yang et al [68] gives design Truncated Corner MSA. This

MSA were fabricated with various thicknesses and studied. The BW of the antenna is

directly proportional to the thickness of the substrate. In this design ,U-slot and L-

probe techniques were used. It overcomes the impedance mismatching of normal probe

fed MSA when the substrate thickness was increased.

Vivek Singh Rathor and J.P.Saini [69] presented a paper where a compact size

MSA has been designed having good impedance matching as well as high antenna effi-

ciency of about of about 90 % is achieved. The proposed antenna have larger impedance

bandwidth of 36.2 % and 56.165 % covering the frequency range from 0.189 GHZ -

4.601 GHZ and 4.655 GHZ-8.29 GHZ which is suitable for Wi-MAX and WLAN. The

paper uses specific pattern of MSA.

A book Printed Circuit Board by Willer C. Bosshart [70] provides detail study

and fabrication steps in designing PCB. Here basic principle, necessity of PCB in cir-

cuit field, types of PCB, and design steps of PCB is nicely explained by experienced

JJT University 58


professionals. This book gives steps of PCB fabrication as layout, planning, artwork

generation, material selection, film master preparation, UV exposure, etching process,

scrubbing, drilling, all types of PCB , with various sizes. Using CAD design, much

more information related to printed circuit board is involved in this book which is very

much usefully to the users.

Basic vector network analysis is providing by Agilent ENA-L RF Network

Analyzers [71] This can be used for wide range of applications There are two basic

modules available as E5061A (300 kHz to 1.5 GHz) and E5062A (300 kHz to 3 GHz).

The data sheet provided by Agilent gives pictures of the analyzer and talks about the

GUI and its use while analyzing various MSA.

Simulation of a RMSA given by Zaakri Safa and Zenkouar Lahbib [72] is

presented in this paper. Using HFSS and ADS as a software simulation of a rectangular

patch antenna is carried out. The resonance frequency used in this design is totally

depends on primary design parameters of MSA, this are dimensions of the patch such as,

substrate material, substrate thickness and feeding technique used. The antenna

performance characteristics are depends on perfect design selection in simulations software

and shape variation selection as per requirement. The HFSS and ADS software bases

essentially helps to find shape , substrate , nature and thickness for obtaining desired a

structure with any operating resonance frequencies.

Bandwidth Enhancement Design of Single-Layer Slotted CMSA presented by Jui-Han

Lu [73] slot-loaded CMSA with bandwidth improvement this broadband design can be

easily generated by adjusting the narrow rectangular slots. The obtained impedance

bandwidth of the proposed design reaches more than 2.3 times that of the normal JJT University 59


CMSAs.

Atinder Pal Singh et al [74] investigated the dimensions of performance in Linearly

Polarized Edge Fed Rectangular patch antenna where ROGERSs material is used as

substrate. This design is for the application WLAN or Wi-Fi applications at resonant

frequency of 2.4835 GHz comes in ISM free band. Various performance properties are

analyzed for the optimized design using Ansoft HFSS. Rectangular MSA presented in this

paper uses various substrate materials.

Design of low cost small size, low profile antenna is presented in this paper by Govardhani

Immadi et al [75] where Coaxial feed technique is used for MSA, at resonant

frequency 2.4 GHz Bluetooth applications. The "I" shaped MSA developed in this design

works well at the required 2.4GHz Bluetooth frequency band. The paper provides three

dimensional pictorial views of the antenna along with graphical presentation of return

loss, VSWR, Axial Ratio etc.

Antenna Basic Concepts along with applications provided by Pulse Electronics on

www.pulseelectronics.com [76] gives easy to understand literature in terms of def-

initions of various concepts like bandwidth, gain, VSWR, radiation pattern, return

loss etc. it also provides diagrammatically presentations of all the concepts. It shows

picture of placement of critical antenna. Antenna mounting is important to result

better performance, if antenna install on trunk or hood the results are not good but

function will be better if it is mounted on the roof of a car. Size, shape and type of

antenna plays very important role in performance, there for it are necessary to know

knowledge about the vehicle. Manual says The metal tinting will work as a shield

and hence it will not allow signals to pass through the glass so do not amount a glass

mount antenna on the rear window of a vehicle. Because metal has been used to reduce

JJT University 60


ultraviolet light.

Antenna Measurement System (WL-AMS-A) developed by Akademika [77]

has been designed to Measure and test various parameters of Antennas, This sys-

tem consists of a wide band PLL based source and detector module working up to

3GHz, a very sturdy nonmagnetic transmitter and receiver stand, Universal Antenna

Mount with plug and fit assembly and radiation pattern plotting software.Antenna

Measurement Trainer System (WL-AMS-A) is to test the fabricated MSA’s in real life

environment.

Antenna performance parameter radiation pattern investigation of elements MSA array

presented by S. M. MahfuzAlam et al [78] gives equations of magnetic and electric

field for elements patch antenna array. Here antennas are analyzed to observe the effects

of dielectric constant of patch element on fringing field. The results from the derived

equations are compared with PCCAD 5.0 software simulation results. The software

results and experimental results comparison shows that the derived equations can be

satisfactorily used for any elements of patch antenna array and any phase displacement

between two patch elements.

Analysis of radiation patterns of rectangular MSAs with uniform substrate is given

by A. Boualleg and N. Merabtine [79]. In this paper the study and analysis of

performances of the rectangular patches is carried and discussed the aperture mod-

els for calculating the radiation patterns of the antenna using the Fourier integrals.

The resonance problem has also been studied. E-plane and H-plane gains of MSA.

Three-dimensional gain patterns also provided for better understanding of rectangular

patches. JJT University 61


2.2 Review Observations

To understand more about MSA’s total 79 publications of previous researchers includ-

ing operational manuals (specific tools used to investigate performance of MSA’s) have

been referred. The summary of literature review w. r. t. simulation, radiation pat-

tern fabrication, Return loss, VSWR, Bandwidth, impedance and shape is as shown

in Figure 2.1.

Figure 2.1: Literature Review Summary: Motivational Parameters

Most of the researchers have concentrated their work radiation pattern (79.71 %) and

simulation (62.32 %) of rectangular MSA’s (59.42 %). Most of the researchers who

have actually manufactured their antennas and tested their results to validate

simulated results for few parameters only. Most of the researchers are increasing the

bandwidth and performances by specific shapes of rectangular MSA’s. Also literature

review shows that there have been less emphasize on circular (14.49 %) and irregular

geometrical shape MSAs (13.04 %).

JJT University 62


Figure 2.2: Literature Review Summary: Operating Frequencies of MSAs

Operating frequencies and respective percentage bandwidths of few typical research

work referred in literature review publications (P16, P18, P31 etc.) are as follows: • P16 (FC = 09.20 and % BW = 2.50) • P18 (FC = 01.45 and % BW = 2.48) • P31 (FC = 02.38 and % BW = 2.10) • P35 (FC = 40.00 and % BW = 2.04) • P45 (FC = 10.00 and % BW = 2.48) • P52 (FC = 01.86 and % BW = 2.15) • P54 (FC = 07.00 and % BW = 2.48) • P58 (FC = 06.60 and % BW = 2.25) • P62 (FC = 20.00 and % BW = 2.25)

JJT University 63


• P74 (FC = 10.00 and % BW = 2.48) • P75 (FC = 11.00 and % BW = 2.40)

Important Observations:

Most of researchers worked on various subjects of interests are as follows: 1. RMSA as shape of their MSAs 2. 1.6 mm as their substrate thickness 3. Glass Epoxy (FR4) as their substrate material 4. Simulation (HFSS) followed by fabrication as their methodology

5. Gain, Bandwidth, Radiation Pattern as their interested Parameters 6.

2.4 GHz to 2.48 GHz (ISM band) as their operating frequency 7. Vector Network Analyzer (VNA) as their Testing Tool

Figure 2.2 shows out of 79 references More than 67 % of the researchers related with

wireless communication are working in frequency range of 2.4 GHz to 2.48 GHz (ISM

band). It quite apparent, because of most of the applications in wireless communication

follows the operating frequency in the vicinity of 2.48 GHz. The important publications

[16, 18, 31, 45, 52, 54, 58, 74, 75] from the literature review as shown in Figure 2.3

also indicates the focused % bandwidth (less than 10) and operating frequency (around

2.48 GHz). 1. Garage door openers, alarm systems: 40 MHz 2. Cordless phones: 40-50MHz, 900 MHz, 2.4 GHz and 5.8 GHz 3. Baby monitors: 49 MHz

JJT University 64


Figure 2.3: Interesting Percentage Bandwidths and Operating Frequencies

4. Radio controlled toys : 27-75 MHz 5. Wildlife tracking collars: 215-220 MHz 6. MIR space station: 145-437 MHz 7. Cell phones: 824-849MHz, 869-894 MHz and 1850-1990 MHz

8. Public safety (fire, police, ambulance): 849-869 MHz 9. RADAR for Air traffic control : 960 MHz-1.215 GHz

10. GPS : 1.227-1.575 MHz 11. Satellite radio: 2.3 GHz

12. WiFi/802.11b/g and Bluetooth: 2.4 GHz 13. Zigbee/802.15.4 : 868 MHz, 915 MHz and 2.4 GHz 14. Microwave ovens: 2.4 Ghz 15. TV: 54-216 (VHF 2-13): 470-806 MHz

16. Ultra-wide-band : 3.1-10.6 GHz JJT University 65


Figure ?? shows Out of 79 references More than 97 % of the researchers related with

wireless communication are working with % Bandwidth less than 10 %. As most of the

wireless communication applications need selection of specific frequency, It is quite

apparent to have less % bandwidth.

Figure 2.4: Literature Review Summary: Percentage Bandwidths of MSAs

Important Observations:

Most of researchers not worked on following subjects of interests are as follows: 1. Non-Linearity as shape of their MSAs 2. Thickness Variations while doing geometric variations 3. Substrate Material Variations

4. Patch platting material variations while forming the patch of MSAs 5. Antenna Measurement System (AMS) as validation tool

6. Cross-polarization, Directivity, Antenna Factor, FNBW and HPBW as parame-

ters 7. Actual Field Implementation and real time applications of their MSAs

JJT University 66


Therefore, the focus of the work presented in this thesis not only related with subject of

interest that Most of researchers have worked on, but also address the interesting matter

where most of the researchers have not focused on.

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