yacouba coulibaly, halim boutayeb and tayeb a. denidni

1

INRS- Énergie Matériaux Télécommunications Montréal, Québec, Canada

Gain Enhancement of a Dielectric Resonator Antenna Using a Cylindrical

Electromagnetic Crystal Substrate

Yacouba Coulibaly, Yacouba Coulibaly, Halim Boutayeb and and Tayeb A. DenidniTayeb A. Denidni

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• Introduction• Antenna Configuration• Simulation Results• Measurements• Conclusion

Outline

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Inconvenient of a Dielectric Resonator Antenna:

low gain

Introduction

Advantages of a Dielectric Resonator Antenna (DRA)

Low losses

Reduced sized

High radiation efficiency

High density integration

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Introduction (cont.)

To improve the radiations characteristics of the DRA, few studies have been proposed:

The DRA has been placed on different ground planes shapes

Coaxially corrugated.

Strip corrugated.

Mushroom-like Electromagnetic Bang Gap (EBG) substrate.

5


Introduction (cont.)

Design Objectives

Use a circularly periodic EBG to increase the gain of a cylindrical DRA.

Exciting the fundamental mode

Have the same radiation pattern shapes with or without the EBG substrate

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Antenna Design

Description:A Dielectric Resonator (DR) :

The DRA has a radius R=15mm, a height hd=10.5mm,and a

permittivity εdra=31.5. .

A Coaxial feed line:

The coaxial line is at a distance of 9

mm from the center.A circular EBG :

Printed on a substrate of permittivity ε2=2.2 and thickness

h=3.2mm. The distance from one strip to the following one is g=2mm. The periods for the strips is Pr2=24.6mm.

The metallic via have a radius a=2mm, and they are disposed with the same transversal period and the same radial period Pr2=23.6mm .

To p V ie w

S id e V ie w

x

y

z

x

S u b s tr a teG r o u n d p lan e

Via

g

P r1

P r1

P r1

P r2

P r2

P r2

Viad iam eter = a

D R A

E x c ita t io n( C o ax ia l lin e)

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Simulated return loss Simulated return loss (with Ansoft HFSS)(with Ansoft HFSS) of the antenna with of the antenna with and without the EBG substrateand without the EBG substrate

Simulated results

2,1 2,4-40

-35

-30

-25

-20

-15

-10

-5

0

With EBG Without EBG

S11

(d

B)

Freq (GHz)

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Simulated gain (with Ansoft HFSS) of the antenna with and Simulated gain (with Ansoft HFSS) of the antenna with and without the EBG substratewithout the EBG substrate

Results:

•The gain is increased by 3 dB due:

• to the reduction of the surface waves.• to the coupling between the DRA and the circular EBG (mainly).

Simulated results (cont)

2,10 2,15 2,20 2,25 2,30 2,35 2,405

6

7

8

9

10 With EBG Without EBG

Ga

in (

dB

)

Freq (GHz)

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Simulated radiation patterns at 2.25 GHz, in both the E- and Simulated radiation patterns at 2.25 GHz, in both the E- and H-Plane, with and without the EBG substrateH-Plane, with and without the EBG substrate

Results:

•The EBG structure improves the gain

•The back radiation decrease

Simulated results (cont)

-10

-5

0

5

100

30

60

90

120

150

180

210

240

270

300

330

-10

-5

0

5

10

E- plane H- plane

2.25GHz

Without EBG With EBG

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Experimental results

Photographs of the fabricated antenna prototypesPhotographs of the fabricated antenna prototypes

DRA aloneDRA alone DRA with cylindrical DRA with cylindrical EBG substrateEBG substrate

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Experimental results

2,10 2,15 2,20 2,25 2,30 2,35 2,40-30

-20

-10

0

S11

(dB

)

Frequency (GHz)

Without EBG With EBG

Measured return loss of the antenna with and without the Measured return loss of the antenna with and without the EBG substrateEBG substrate

Network AnalyzerNetwork Analyzer

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Experimental results (cont)

Measured gain (in an anechoic chamber at INRS) with and Measured gain (in an anechoic chamber at INRS) with and without the EBG substratewithout the EBG substrate

2,10 2,15 2,20 2,25 2,30 2,35 2,404,0

4,5

5,0

5,5

6,0

6,5

7,0

7,5

8,0

8,5

9,0

Ga

in(d

B)

Frequency(GHz)

With EBG Witout EBG

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H-planeH-planeE-planeE-plane

Measured radiation patterns with and without the EBG Measured radiation patterns with and without the EBG substratesubstrate

-10

0

100

30

60

90

120

150

180

210

240

270

300

330

-10

0

10

W ith EBG Without EBG

-10

0

100

30

60

90

120

150

180

210

240

270

300

330

-10

0

10

W ith EBG Without EBG

Experimental results (cont)

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The gain enhancement of a DRA has been investigated and good performances have been achieved

By adding the EBG substrate, the radiation characteristics have been significantly improved

The coupling between the cylindrical DRA and the reduction of the surfaces waves enhance the gain of the antenna

Conclusion

Perspectives:

• Investigation of elliptical EBG structures;• Design of elliptical patch antennas and elliptical DRAs integrated on elliptical EBG substrates, for Satellites communications applications (circular polarization).

yacouba coulibaly, halim boutayeb and tayeb a. denidni

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