new concept, theory, and advanced design of resonant ...a cylindrical dielectric resonator antenna...

New Concept, Theory, and Advanced Design of Resonant Cavity Antenna

Koushik DuttaDepartment of Electronics and Communication Engineering

Netaji Subhash Engineering College, Kolkata, India

https://www.nsec.ac.in/

Forum for Electromagnetic Research Methods and Application Technologies (FERMAT)

https://www.nsec.ac.in/

Copyright©The use of this work is restricted solely for academicpurposes. The author of this work owns the copyrightand no reproduction in any form is permitted withoutwritten permission by the author.

Dept. of ECE, Netaji Subhash Engineering College 2

AbstractResonant Cavity Antenna (RCA) has been explored with a new concept. Thesuperstrate configurations with their new principle of operation have beendemonstrated to realize a high gain RCA. Indeed, in here, a nontransparent solid metalsheet has been conceived and implemented as a superstrate for the first time. Thisapproach is successful in removing the previous notion of RCA design using partiallyreflecting surface (PRS) as superstrate. RCA is actually a class of high gain antennaworking based on the principle of Fabry-Perot cavity, where a superstrate layer isplaced on top of a primary radiating element (printed or low profile antenna)maintaining a separation of 𝜆𝜆/2. A cylindrical dielectric resonator antenna has beenused as the primary radiator in this investigation. Present studies based on theory andexperimental verifications provide: (i) fully new concept of understanding of Fabry-Perot cavity in microwave domain; (ii) new idea and possibility of using a solid or non-transparent metallic superstrate in realizing an RCA; (iii) concept of aperture fieldsurrounding the superstrate and its contribution to high gain characteristics; (iv)synthesis of superstrate field as a function of superstrate geometry and the technique ofimproving the radiation/gain patterns.


Keywords: Resonant cavity antenna, Fabry-Perot cavity antenna, resonancegain antenna, high gain, aperture field, superstrate

BiographyKoushik Dutta is an Assistant Professor in the Department ofElectronics and Communication Engineering, Netaji SubhashEngineering College, Kolkata, India. After finishing his B.Sc PhysicsHonours, he had received his B.Tech., M.Tech., and PhD degreesfrom Institute of Radio Physics & Electronics, University of Calcutta,India. He has researched in developing high-gain resonant cavityantenna with a new concept and theory. He has published over 30papers in top peer-reviewed Journals and Conferences. Dr Dutta is aSenior Member of IEEE and life member of the Institute of Engineers(India). He is presently associated with editorial boards of severalInternational Journals. He is the Student Activity Chair of IEEEKolkata Section. He received the National Scholarship from MHRD,India in 1999 and IEEE outstanding volunteer Award in 2017. He hasreceived the best paper award at IEEE InCap 2019. His students havealso received several awards in college and conferences for theirresearch projects and publications. His current research interestsinclude dielectric resonator antenna, microstrip-patch antenna,circularly polarized antenna, Fabry-Perot antenna, and polarizationmodulation.


Fabry-Perot Cavity Antenna: Basic Concepts

Working Principle: Fabry-PerotAntenna Feature: Very high gain

Commonly Known as:Resonant Cavity Antenna (RCA)

or Resonance Gain Antenna (RGA)

Primary radiator alone

DRAmicrostrip

patch

Primary radiator with superstrate

CavityCavity

Radiation Patterns

h ≈ λ/2superstrate superstrate

h≈ λ/2

Radiation Patterns


Fabry-Perot Cavity Antenna: Basic Concepts

Advantages(i) Very high gain, (ii) Substitution of antenna array,(iii)Smaller size,(iv) Improvement of antenna

characteristics: Bandwidth, cross-polarization level, side-lobe level, back radiation etc.

(v) Protection from environment

Ray Tracing

directive pattern


The First Investigation [1956]

Waveguide-fed RCAs proposed for the first time: (a) cylindrical cavity with metal-stripsuperstrate; (b) rectangular cavity with wire-grid superstrate; (c) rectangular cavity loadedby an array of circular patches supported by a polystyrene plate.

Named as “reflex cavity antenna”

(a) (b) (c)

partially reflecting sheet


Shen, et. al., “Effect of superstrate on radiated fieldof probe fed microstrip patch antenna” IEE Proc.Microw. Antennas Propag., vol. 148, no. 3, pp. 141–146, June 2001.

Lee & Mittra, “Application of electromagneticbandgap (EBG) superstrates with controllable defectsfor a class of patch antennas as spatial angular filters”IEEE TAP, 53, 1, 2005.

Attia et. al, “Analytical model for calculating theradiation field of microstrip antennas with artificialmagnetic superstrates: theory and experiment” IEEETAP., 59, 5, 2011.

Feresidis and Vardaxoglou, “High gain planarantenna using optimized partially reflective surfaces”IEE Proc. Elect. Eng. Microw. Ant. Prop., 148, 6,2001.

Agouzoul et. al, “Design of a high gain hybriddielectric resonator antenna for millimeter-wavesunderground applications” APS-URSI, 2011.

using Partially Reflecting Surface (PRS) superstrateRecent Developments

Radiate throughout the superstrate surface

Method of Analysis

1. Ray Tracing2. Leaky-wave

8Dept. of ECE, Netaji Subhash Engineering College

New Concept: Fully Reflecting Surface (Proposed for the first time)

Advantage simpler, compact, and maintenance free

K. Dutta, et. al, “New approach in designing resonance cavity high gain antenna using nontransparent conducting sheet as the superstrate” IEEE TAP, vol. 63, no. 6, June. 2015.

3.5 4.0 4.5 5.0-30

-25

-20

-15

-10

-5

0

DRA alone

S 11 (

dB)

Frequency (GHz)

measured simulated

E-field at 3.6 GHz E-field at 4.1 GHz

ResonanceEffective relative permittivity

𝜀𝜀𝑟𝑟𝑟𝑟 = (ℎ𝑎𝑎 + ℎ𝑑𝑑) (ℎ𝑑𝑑 ε𝑟𝑟⁄ + ℎ𝑎𝑎)⁄

𝑓𝑓𝑟𝑟 = 𝑓𝑓0 �𝜀𝜀𝑟𝑟𝑟𝑟⁄


Measured Radiation Patterns


-1.0 -0.5 0.0 0.5 1.0

0

100

200

300 H-Plane (yz)

E-Plane (x-z)

Aper

ture

fiel

d (V

/m)

x/a (for E-plane) or y/b (for H-plane)

superstrate

3.6 GHz

-1.0 -0.5 0.0 0.5 1.0

0

100

200

3004.1 GHz


superstrate

H-Plane (yz)

E-Plane (x-z)

Aper

ture

Fie

ld (V

/m)

X

Y

max

min

X

Y

superstrate

Over plane

Over axis

11

Far fieldpatterns

Aperture field distributions

Near field – Far field Relation

-1.0 -0.5 0.0 0.5 1.0

0

100

200

300 H-Plane (yz)

E-Plane (x-z)

Aper

ture

fiel

d (V

/m)


superstrate

Fourier Transform

Inverse Tapered


Major Outcome• Nontransparent superstrate proposed for the first time

• Removed the notion of ‘semi-transparent’ superstrate

• 23% of bandwidth with 12.2 dBi peak gain

• Flat gain over the operating band

• Only drawback is higher side-lobe-level

K. Dutta, D. Guha, C. Kumar, and Y. M. M. Antar, “New approach in designing resonance cavity high gain antenna using nontransparent conducting sheet as the superstrate,” IEEE Trans. Antennas Propag., vol. 63, no. 6, June. 2015.

Reported in


Fabry-Perot Cavity Antenna-2

K. Dutta, et. al, Synthesizing Aperture Fields over Engineered Metal Film Superstrate in aResonance Cavity Antenna for Modifying its Radiation Properties,K. Dutta, D. Guha, and C. Kumar, IEEE Antennas Wireless Propagation Letters, vol. 15,2016.


GaussianInverse tapersuperstrate

farfield

no side lobe

Resultant

lower SLL

farfield

higher SLL

farfield

Concept of aperture synthesis

practical ideal modified


K. Dutta, et. al, “Synthesizing Aperture Fields over Engineered Metal Film Superstrate in a Resonance Cavity Antenna for Modifying its RadiationProperties” IEEE AWPL, vol. 15, 2016.

metal film #1 metal film #2two inverse tapper distribution

DRA

metal film #1 metal film #2slit

ground planeεr

metal film #1 slitdielectric

metal film #2

Top View

Side View

New aperture synthesis approach

Realization


Improved Geometry for Higher Gain

Metal sheet Single Slit (SS) SL-1 SL-2


+ + + + ++ + + + +

+ + +

- - - --- - - --

---

+ + + + ++ + + + +

+ + +

- - - --- - - --

---

slit+ + + + ++ + + + +

+ + + + +

- - - --- - - --

---+

- --

--

+ + + + ++ + + + +

+ + + -- - - --- - - --

---

--

+ + ++ + + +

slots

slit

slots slots

+ + + + ++ + + + +

+ + + + +

--

--

+ +

+ +

- - - --- - - --

--

---+

- + -+ + + + ++ + + + +

+ + + + +

--

--

+ +

+ +

- - - --- - - --

--

---+

- + -

+ + + + ++ + + + +

+ + +

- - - --- - - --

---

Metal sheet Single Slit (SS)

SL-1 SL-2

Schematic Electric Field Vector (side view)


Metal sheet Single Slit (SS)

SL-1 SL-2

Surface Currents over the Superstrate


Experimental validation of new Aperture Synthesis based design

Type Size (area)

Peak Gain(dBi)

SLL(dB)

E-plane H-plane

metal sheet 1.21λ2 12 -7 -7

Metal film with single slit (SS) 0.94λ2 13.9 -11 -12.8SS with a pair of slots (SL-1) 0.94λ2 14.4 -11.9 -14.8

SS with two pairs of slots(SL-2) 0.94λ2 15.2 -13.2 -17


K. Dutta, et. al, “Synthesizing Aperture Fields over Engineered Metal Film Superstrate in a Resonance Cavity Antenna for Modifying its RadiationProperties” IEEE AWPL, vol. 15, 2016.

to a distant point P (r, θ, φ)of direction cosines (l, m, n)

O

X

x Qdxdy

y

γ1

β1α1Y

Z

)cos,cos,(cos)ˆ.ˆ,ˆ.ˆ,ˆ.ˆ(),,(

111 γβαβββ

== zyxnml

φθα cossincos 1 =φθβ sinsincos 1 =

θγ =1

where

Q' mylxr +=.̂β

Kraus & Marhefka,3rd ed. McGraw-Hill, 2002

In spherical polar coordinates

Far-field Aperture field

Aperture fielddistribution E(x, y)

r0r

Radiating Aperture

New Theory for Fabry-Perot Cavity Antenna

21K. Dutta, et. al, “Theory of Controlled Aperture Field for Advanced Superstrate Design of a Resonance Cavity Antenna withImproved Radiations Properties” IEEE TAP, vol. 65, no. 3, pp. 1399 − 1403, 2017.

Over two principal planesφ = 0o or xz-plane

Where,

(1)

and φ = 90o or yz-plane(2)


Meaning of resultant

X

Y

b'b

c'c

a'a

Z

XYground plane

hrDRA

superstrate

δ1 δ0O

E1 E1

E0

-x1δ1

E(x)

Xx1

T+1T-1T0

Its Fourier transform

Power spectral density (PSD) (3)

(4)Dept. of ECE, Netaji Subhash Engineering College 23

δ0

E0E(x)

X

T0

Case 1: When only T0 is presentPower spectral density (PSD) / Radiation Pattern

~side lobe

-4π/δ0 4π/δ00 k

-2λ/δ0 2λ/δ00

main lobe

~ ~~ SLL = )(log10 10 MS PP= -26.9 dB

Independent ofE0 and δ0

Changing pattern with increase in δ0


Case 2: When T-1 and T+1 are presentPower spectral density (PSD) / Radiation Pattern

δ1

E1 E1

-x1δ1

E(x)

Xx1

T+1T-1

-4π/δ1 4π/δ1−2π/x1 −π/x1 2π/x1π/x10k

-2λ/δ1 2λ/δ1−λ/x1 −λ/2x1 λ/x1λ/2x10

main lobe

1st side lobe

2nd side lobe


Case 3: when T0, T-1, and T+1 all present

(4)δ1 δ0

O

E1 E1

E0

-x1δ1

E(x)

Xx1

T+1T-1

T0

under a special condition δ0=δ1

(5)

determines the side lobe and minima locations

The 1st null at zero level

E0≤2E1

condition for zero null


the side lobe locations:

(6)

Changing pattern with change in E0/E1 ratio

-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5

mainlobe

oddlobes

1

sin(θ)

E0/2E1=1.25

0.5

0.25

δ1=δ0=x1/2=λ/2

evenlobes

real limit:


Useful design insights

• Increase in E0, E1, δ0, and δ1 enhances the gain.

• E0/E1 determines the existence as well as magnitude of the odd SLLs.

• Smaller value of x1 pushes the side lobes away from the main beam and makes them insignificant.

δ1 δ0

O

E1 E1

E0

-x1δ1

E(x)

Xx1

T+1T-1

T0

K. Dutta, D. Guha, and C. Kumar, “Theory of Controlled Aperture Field for AdvancedSuperstrate Design of a Resonance Cavity Antenna with Improved Radiations Properties,”IEEE Trans. Antennas Propag., vol. 65, no. 3, pp. 1399−1403, March 2017.

Reported in


Applying the Theory

c'

a'Y

X

c

a

b'b

E1

x1

E1

-x1

E(x)

X

a=2x1

Varying superstrate size


Validation

Design and ValidationReshaping of Superstrate

a'

Y

X

a

b'

bY

X

a

a'

b

b'

etched part 0.5λ × λ


Effect on Far Field Radiation Pattern


3.7 GHz 4.2 GHz

bCDRA

Y

X

a

dm

p

3.7 GHz 4.2 GHz

Further Aperture Field Control: Improvised Geometry


Antenna Prototypes

Prototype-A Prototype-B

Superstrate 10 mil thick FRP substrate (εrs= 4.55)

Spacers Rohacell foam (εr≈1.06-1.08, tanδ = 0.001)

DRA Emerson Cuming’s HiK material (εr=10)

Measurement a) Agilent’s E8363B network analyzer

b) Automated anechoic chamber


Experimental Results


Conclusion

• Compact superstrate (∼0.5λ×1λ )

• Very low SLL ( -24 dB)

• High gain (13.3 dBi)

• Wide bandwidth (20%)

K. Dutta, D. Guha, and C. Kumar, “New Design of Resonance Cavity Antenna by Controlled CurrentDistribution over a Reduced Sized Superstrate to Achieve Improved Gain, Side Lobe Level, Efficiencyover Wide Operating Bandwidth,” IEEE Trans. Antennas Propag., (AP1512-1904: under review)

Reported in

Comparison: Gain over the Frequency


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Radiation Properties,” IEEE Antennas and Wireless Propagation Letters, vol. 15, pp. 1677–1680, 2016.25. K. Dutta, D. Guha and C. Kumar, “Theory of Controlled Aperture Field for Advanced Superstrate Design of a Resonance Cavity Antenna With Improved

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Slide Number 1Slide Number 2Slide Number 3Slide Number 4Slide Number 5Slide Number 6Slide Number 7Slide Number 8Slide Number 9Slide Number 10Physical Insight Aperture field distributionSlide Number 12Major OutcomeSlide Number 14Slide Number 15Slide Number 16Slide Number 17Slide Number 18Slide Number 19Slide Number 20Slide Number 21Slide Number 22Aperture field distribution over the superstrateSlide Number 24Slide Number 25Slide Number 26Slide Number 27Useful design insightsSlide Number 29Slide Number 30Slide Number 31Slide Number 32Slide Number 33Slide Number 34ConclusionSlide Number 36Slide Number 37

new concept, theory, and advanced design of resonant ...a cylindrical dielectric resonator antenna...

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