1

Debatosh Guha Institute of Radio Physics and Electronics,

University of Calcutta, India

Mysteries of DRA Modes Unresolved Issues for the Future

University College of Science and Technology 1914-2014

On the World Map

● KOLKATA

Our Teachers

C V Raman 1888-1970 NL 1930

S K Mitra 1890-1963

R. N. Tagore 1861-1941 NL 1913

S N Bose 1894-1974

M N Saha 1893-1956

1895 Demonstrated a mechanical operation using WIRELESS at 2.5 GHz

Our Heritage 1895

transmitting Horn

receiving Horn

Bose’s Pyramidal Horn

R e s t i s H i s t o r y

Today’s Presentation

Unknown Mode in Known DRA

31 Years ago 1983-2014

7

Cylindrical-DRA

IEEE MTT Dec. 1984

HEM11δ

m

TM01δ

e m

TE01δ

Mode Nomenclature

TE0 n p+δ TM0 n p+δ HEMm n p+δ

m: number of full-period variations of fields along the azimuth n: half-wave variation along radius (field between center and the periphery) ‘p+δ’: half-wave variation along z-axis of the cylinder

HEM 11δ

Isolated Resonator

10

TM 01δ

Isolated Resonator

11

H

E

Theoretical HEM 12δ Mode

Boundary condition does not allow any ground plane Isolated Resonator

Does it Radiate?

It should

Address the Challange

Boundary Condition demands Horizontal current in place metal

13

x

y

x

z

New approach to realize a current ribbon ??

grounded substrate circular patch

Non-resonant Microstrip Patch

working as a current ribbon

Probe current

First Examination

5.0 5.5 6.0 6.5 7.0 7.5 8.0-30

-25

-20

-15

-10

-5

0

7.2 GHzS 11(d

B)

Frequency(GHz)

4.6 mm

11.5 mm

εr = 38

Kajfez’s Sample + our Technique

-150 -100 -50 0 50 100 150-50

-40

-30

-20

-10

0

10

cross-polarized

co-polarized

Dire

ctivi

ty(d

Bi)

Theta(degree)

E Plane H Plane

Gain at 7.24 GHz

14

experiments

NMP

DRA

5 6 7

-30

-20

-10

0

5 6 7

S 11

(dB)

measured

Frequency (GHz)

simulated

DRA: εr,d = 10, a = 10 mm, h = 10 mm. NMP r = 5 mm, εr,s = 2.33, t=1.575mm;

2 3 4 5 6 7 82 3 4 5 6 7 8-5

-4

-3

-2

-1

0

meas

back

S 11 (

dB)

Frequency (GHz)

simu

front

when the feed is alone

Radiations

-180 -120 -60 0 60 120 180

-20

-10

0

10

-180 -120 -60 0 60 120 180

-20

-10

0

10 meas

Dire

ctivi

ty (d

Bi)

Angle (degree)

simu co-polarized

cross-polarized

-180 -120 -60 0 60 120 180

-20

-10

0

10

-180 -120 -60 0 60 120 180

-20

-10

0

10

Dire

ctivi

ty (d

Bi)

Angle (degree)

simu meas

co-polarized

cross-polarized

E-plane H-plane

f = 7.4 GHz

after 3 decades

16 D. Guha, et al. IEEE AP Transactions, January, 2012

Design Limitations? Unknown Mysteries

zinc tungstate composite

Any limitation in DRA diameter?

Any limitation in DRA height?

Any limitation imposed by the DRA material?

D. Guha, et al. IEEE AP Mag. August 2014

Any other Technique?

Fully planar should be most advantageous; should it be like this?

No, not so straight forward.

Mysteries lie in Current Ribbon with matching; solution needs a different approach.

D. Guha, et al. IEEE AP-S Memphis, 2014

YES! Much Easier and Robust Technique has been developed recently and reported

Excitation Mechanism? Completely NEW

Feed is conventional using vertical Probe.

Ground plane (GP) is a metal sheet.

Boundary condition of GP has been modified favorably which can support HEM12δ mode.

Yet any Other Technique?

Ground Plane

Rect Trough

Probe-Pin

Role of Embedded Truough

ground plane with trough

The Results

RADIATES

RADIATES

D. Guha, et al. IEEE AWPL, 2014

TROUGH causes

Yet Any Other?

Definitely YES

1

Two Different Techniques have been Explored Recently

Composite Aperture – to realize equivalent Magnetic & Electric Dipoles as new Feed

Under investigation………

An Open Book to YOU

2

• Aperture introduces no metal.

• Favors required boundary condition for HEM12δ mode.

• Suitable for HEM11δ mode too.

Suitable Aperture

Aperture Coupled

Why?

εr = 10

Aperture-Feed Explored HEM12δ + HEM11δ

20mm

10mm

3 4 5 6 7 8

-30

-20

-10

0

S 11(d

B)

Freq.(GHz)

Feed1

3 4 5 6 7 8

-30

-20

-10

0

S 11(d

B)

Freq.(GHz)

Feed 2

3 4 5 6 7 8

-30

-20

-10

0

S 11(d

B)

Freq.(GHz)

Feed 3

Feed 1

Feed 2

Feed 3

1 2 3

4

3 4 5 6 7 8

-30

-20

-10

0

HEM12δ

S 11(d

B)

Freq.(GHz)

1 2 3 4

HEM11δ

Impedance vs Feed

2

1

3

4

0.2 0.5 1.0 2.0 5.0

-0.2j

0.2j

-0.5j

0.5j

-1.0j

1.0j

-2.0j

2.0j

-5.0j

5.0j

Feed#1

Feed#2

Feed#3

Feed#4

Characterize the Feed

Choose the Right Feed for Higher Mode

Feed1 Feed2 Feed3 Feed40

5

10

15

20

25

30

35

RL Co-Cross Isolation Gain

0.2 0.5 1.0 2.0 5.0

-0.2j

0.2j

-0.5j

0.5j

-1.0j

1.0j

-2.0j

2.0j

-5.0j

5.0j

Feed#1 Feed#2 Feed#3

Feed#4

1

2

3

4

What about Dominant Mode?

Select the Optimum One

HEM11δ HEM12δ

Feed#1 Feed#2 Feed#3 Feed#40

5

10

15

20

25

30

35

RL Co-Cross Isolation Gain (dB/dBi)

-180 -120 -60 0 60 120 180

-30

-20

-10

0

10

Cross-pol

Co-pol

E-Pl

ane

Gai

n (d

Bi)

Angle(degree)

Feed1 Feed2 Feed3 Feed4

-180 -120 -60 0 60 120 180-30

-20

-10

0

10

Cross-pol

Co-pol

H-Pl

ane

Gai

n (d

Bi)

Angle(degree)

Feed1 Feed2 Feed3 Feed4

-180 -120 -60 0 60 120 180-30

-20

-10

0

10

Cross-pol

Co-pol

E-Pl

ane

Gai

n (d

Bi)

Angle(degree)

Feed1 Feed2 Feed3 Feed4

Radiation Patterns

HEM11δ HEM12δ

-180 -120 -60 0 60 120 180-30

-20

-10

0

10

Cross-pol

H-Pl

ane

Gai

n(dB

i)

Angle (degree)

Feed1 Feed2 Feed3 Feed4

Co-pol

Optimized Aperture

Optimized Feed Line

a

b

b a

Optimum Parameters

Table of Parameters Parameters Optimized Value

(mm) In Terms of λ

a 10 0.13λ1 (0.24λ2)

b 2 0.03λ1(0.05λ2)

w 3.6 0.05λ1(0.09λ2)

l 39 0.5λ1(0.95λ2)

p 9 0.12λ1(0.22λ2)

q 3.95 0.05λ1(0.1λ2)

K 11.5 0.15λ1(0.28λ2)

Frequency (f) Wavelength (λ)

3.85GHz(f1) 78mm (λ1)

7.35GHz (f2) 41mm(λ2)

l

w

b

k

q

q

p

l

w

The Prototype

Viewed from Feed-line side

3 4 5 6 7 8-30

-20

-10

0

3 4 5 6 7 8-30

-20

-10

0

Freq(GHz)

measured simulated

HEM12d mode

S 11 (d

B)

HEM11d mode

3 4 5 6 7 8

-30

-20

-10

0

HEM12d mode

S 11(d

B)

Freq (GHz)

measured simulated

HEM11d mode

Measured Results

-120 -60 0 60 120-30

-20

-10

0

10

H-Pl

ane

Gai

n (d

Bi)

Angle(degree)

measured

cross pol

co pol

simulated

-120 -60 0 60 120-30

-20

-10

0

10

H-Pl

ane

Gai

n (d

Bi)

Angle(degree)

measured

co pol

cross pol

simulated

-120 -60 0 60 120-30

-20

-10

0

10

E-Pl

ane

Gai

n (d

Bi)

Angle(degree)

measured

cross pol

co pol

simulated

Measured Radiations

? -120 -60 0 60 120-30

-20

-10

0

10

E-Pl

ane

Gai

n(dB

i)

Angle(degree)

measured

cross pol

co pol

simulated

a i r f i l m

Interesting Observation

Air-film Thickness~ (0.02-0.04)mm

-120 -60 0 60 120-30

-20

-10

0

H-Pl

ane

Gai

n (d

Bi)

Angle(degree)

measured

cross pol

co pol

simulated (with airfilm)

Closely Follow HEM12δ

-120 -60 0 60 120-30

-20

-10

0

E-Pl

ane

Gai

n (d

Bi)

Angle Theta (degree)

measured

cross pol

co pol

simulated (with airfilm)

-120 -60 0 60 120-30

-20

-10

0

H-Pl

ane

Gai

n (d

Bi)

Angle(degree)

measured

co pol

cross pol

simulated (with airfilm)

-120 -60 0 60 120-30

-20

-10

0

-120 -60 0 60 120-30

-20

-10

0

E-Pl

ane

Gai

n (d

Bi)

Simulated (with airfilm)

co pol

cross pol

E-Pl

ane

Gai

n (d

Bi)

Angle(degree)

measured

Effect of the air-film

HEM12δ

HEM11δ

Radiation over the Operating Band

Frequency(GHz) 7 7.5 7.2 7.1 7.3 7.4

Location on the spectrum

Is it a Strawberry ?

Unconventional Pattern providing larger Beamwidth

•New feed for CDRA with HEM11δ & HEM12δ modes simultaneously.

• Both the modes with comparable Bandwidth, Gain and Patterns.

•Dual mode dual-band antenna with identical radiations

•Unavoidable air-gap is a new finding, which adds a new feature.

Interesting Features

Known Modes in Unknown Structures

Mongia et al Elect. Lett. 29(17) 1530-1531, 1993.

TM01δ mode after a decade

43

5 10 15-20

-15

-10

-5

0

S 11 (d

B)

Frequency (GHz)

Ittipiboon, Petosa, Thirakoune, Bandwidth enhancement of a monopole using dielectric antenna resonator loading, ANTEM, Canada, Aug. 2002

Marriage of two Monopoles

Lapierre, Antar, Ittipiboon, Petosa, IEEE MWCL, Jan. 2005.

BW 2.9:1

US patent no.6940463 Sept. 2005

Problem bestowed upon

5 10 15 20-40

-30

-20

-10

0 DRR :l= 4.4 mm monopole:l=10 mm DRR+monopole:l=10 mm

Ret

urn

Loss

(dB

)

Frequency (GHz)

?

reduced length monopole 0.6l = λ2/4

Inside the Modes Mystery of BW?

a) Design Frequency first resonances:f1 , third resonances : f3 are related as fH ≈ 2.5 fL. b) Monopole Parameters : Length : l = λL/4 Radius : s≥ r ≥ s/2 (c) DRA Parameters : Spacing s is important for second and third resonances and it is optimum when 0.016 λL ≥ s ≥ 0.013λL and b = r + s, a = b/ 0.3, 0.5 l ≥ h ≥ 0.4l . Finally, εr value is extracted from the TM01 resonance formula

Guha, Antar, Ittipiboon, Petosa, Lee, IEEE AWPL, vol. 5, 2006.

Design Becomes Easy

Design Freq. GHz

λL mm

Antenna Parameters

l mm

s mm

r mm

b mm

a mm

h mm

εr

#1 2-5 150 37.5 1.9 1.0 2.9 9.5 16 25

#2 3 -8 100 25.0 1.4 0.65 1.95 6.5 11 18

#3 5 -13 60 15.0 0.84 0.65 1.49 5.0 6 10

Paper design as per Design Guideline

Verification

2 4 6 8 10 12-30

-20

-10

#1 #2 #3

S 11 (

dB)

Frequency (GHz)

measured

S 11 (

dB)

Frequency (GHz)4 6 8 10 12-30

-25

-20

-15

-10

-5

simulation

Improved Bandwidth?

Definitely Yes! If we can add identical mode(s)

How ? Adding resonators? or Resonances?

Let’s examine the primary resonator if it can help!

-150 -100 -50 0 50 100 150-50

-40

-30

-20

-10

0

10

Gain

(dBi

)

Angle Theta (degree)

6 GHz 20 GHz

2009-12

How to accommodate that mode?

By shaping the DRA

What’s New?

DRR radius = 4.2 mm DRR height = 4.4 mm inner cut rad=1.3 mm εr=10 MP height=10 mm MP rad=0.65 mm

5 10 15 20 25 30-40

-30

-20

-10

0

S 11 (d

B)

Frequency (GHz)

-150 -100 -50 0 50 100 150-50

-40

-30

-20

-10

0

10Di

rect

ivity

(dB

i)

Angle theta (degree)

f=6.8 GHz 13 GHz 16 GHz 20 Ghz

Radiations over the Band

52

The Physical Insight UWB ?

5 10 15 20 25-50

-40

-30

-20

-10

0

5 10 15 20 25-50

-40

-30

-20

-10

0

S 11 (d

B)

Frequency (GHz)

5 10 15 20 25-50

-40

-30

-20

-10

0

5 10 15 20 25-50

-40

-30

-20

-10

0

S 11 (d

B)

Frequency (GHz)5 10 15 20 25-50

-40

-30

-20

-10

0

5 10 15 20 25-50

-40

-30

-20

-10

0

a=5.01 mmS 11

(dB)

Frequency (GHz)

Only MP MP-DRA (Hybrid)

HDRR Alone

Detailed Studies

D. Guha, B. Gupta and Y. M. M. Antar, IEEE AWPL , vol. 8 , 2009

D. Guha, B. Gupta and Y. M. M. Antar, IEEE AP Transactions, Jan., 2012

D. Guha, et al, IEEE AWPL, vol. 5, 2006.

Newer Modes?

and wider Bandwidth?

Yes, Possible

5 10 15 20 25-50

-40

-30

-20

-10

0

S 11 (d

B)

f (GHz)

BW 148.4%

10 20 30 40 50 60 70 80-40

-35

-30

-25

-20

-15

-10

-5

0

S 11 (d

B)

Frequency GHz

BW 177.5% 54

Composite DRA Structure

D. Guha and Y. Antar: IEEE AP Transactions, Dec. 2006

D. Guha and Y. Antar: IEEE AP Transactions Oct. 2006

Monopole-like Pattern

55

New Approach New Configurations

A′ A

Cylindrical DRA

Coaxial Probe

Central Dielectric Cylinder

30% Bandwidth 0.1λ0 by 0.6 λ0

rad = 10 mm, height= 10 mm εr= 10 central cylinder: rad = 4.143 mm, height= 10 mm εr= 12 probe length = 9.2 mm, radius = 0.55 mm.

56

The Resonances

2.5 3.0 3.5 4.0 4.5-40

-30

-20

-10

0

Measured SimulationRe

turn

Los

s (d

B)

Frequency (GHz)

Probe as monopole

by DRA

HEM 11d mode 57

Half of a Hemisphere

Half of a Hemisphere Electromagnetically coupled two Half- Hemispherical DRAs

Composite DRA

measured

2.5 3.0 3.5 4.0 4.5-70

-60

-50

-40

-30

-20

-10

0

Retu

rn L

oss

(dB)

Frequency (GHz)

40% Bandwidth with 4.8 dBi peak gain.

59

Radiation Patterns

-150 -100 -50 0 50 100 150-30

-20

-10

0

10

simulated measured

Gai

n (d

Bi)

Angle θ (degree)

-150 -100 -50 0 50 100 150-30

-20

-10

0

10

simulated measured

Gai

n (d

Bi)

Angle θ (degree)

-150 -100 -50 0 50 100 150-30

-20

-10

0

10

simulated measured

Gai

n (d

Bi)

Angle θ (degree)

simulated measured

-150 -100 -50 0 50 100 150-30

-20

-10

0

10

Gai

n (d

Bi)

Angle θ (degree)

φ = 0o φ = 90o

2.9 GHz

3.7 GHz

60

Symmetric Patterns? how to obtain

Need Modal Symmetry Structural Symmetry

Hemispherical DRA HDRA

Half-HDRA h-HDRA

Quarter-HDRA q-HDRA

61

Quarter and Composite

Introduces Modal Symmetry

Are they Different Modes ?

2.5 3.0 3.5 4.0 4.5-40

-30

-20

-10

0

S 11 (d

B)

Frequency (GHz)

10 mm 11 mm 12 mm 13 mm

HEM11δ -like mode TM101 mode

63

Perfect Symmetry

2.5 3.0 3.5 4.0 4.5-20

-10

0

2.5 3.0 3.5 4.0 4.5-20

-10

0

S 11 (d

B)Frequency (GHz)

simu meas

64

Radiation Patterns

-150 -100 -50 0 50 100 150-30

-20

-10

0

10

-150 -100 -50 0 50 100 150-30

-20

-10

0

10

Cross-polarized

Co-polarized simu

Gai

n (d

B)

Angle theta (degree)

meas

-150 -100 -50 0 50 100 150-30

-20

-10

0

10

-150 -100 -50 0 50 100 150-30

-20

-10

0

10

Gai

n (d

Bi)

Angle theta (degree)

simu

Cross-polarized

Co-polarized meas

-150 -100 -50 0 50 100 150-30

-20

-10

0

10

-150 -100 -50 0 50 100 150-30

-20

-10

0

10

Gai

n (d

Bi)

Angle theta (degree)

simu

Cross-polarized

Co-polarized meas

-150 -100 -50 0 50 100 150-30

-20

-10

0

10

-150 -100 -50 0 50 100 150-30

-20

-10

0

10

Gai

n (d

Bi)

Angle theta (degree)

simu

Cross-polarized

Co-polarized meas

Φ=0 deg Φ=45 deg

3.1 GHz

3.51 GHz

65

Compare

-150 -100 -50 0 50 100 150-15

-10

-5

0

5

Gai

n (d

Bi)

Angle theta (degree)

Frequency=3.3 GHz

-150 -100 -50 0 50 100 150-15

-10

-5

0

5

Gai

n (d

Bi)

Angle theta (degree)

Frequency=3.3 GHz

-150 -100 -50 0 50 100 150-15

-10

-5

0

5

Gai

n (d

Bi)

Angle theta (degree)

Frequency=3.7 GHzΦ=900 Φ=00

-150 -100 -50 0 50 100 150-15

-10

-5

0

5

Gai

n(dB

i)

Angle theta (degree)

Frequency=3.7 GHz

66

Concluding Remarks

DRA is still an Open Book; Not event its 30% Explored. DRA researchers should have more insight and serious attention

Resonator, Material, and Antenna need to be addressed together

Next Breakthrough Awaiting New Dielectric Materials

67

I hope to come with new information for you shortly : Mode filtering technique as a potential tool for DRA engineers. Newer Feed to resolve major DRA issues in integrated platform - which is supposed to be very hard task.

2002 Research Studies Press

2007Artech House 2007 McGraw Hill 2008 Elsevier

Dielectric Resonator Antennas: K. M. Luk & K. W. Leung

Dielectric Resonator Antenna Handbook: A. Petosa

Antenna Engineering Handbook: J. L. Volakis Ed.

Dielectric Materials for Wireless Comm: M. T. Sebastian

Related Books

This approach can be extended to other DRA geometries.

Remarks

New Lights for future applications……………………

Behind this small contribution