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Antenna-in-Package (AiP) Technology

Y. P. Zhang, FIEEE

Micro Radio Group

Integrated System Research Lab

School of Electrical and Electronic Engineering

Nanyang Technological University (NTU)

Singapore

Forum for Electromagnetic Research Methods and Application Technologies (FERMAT)

by

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Abstract

The antenna-in-package (AiP ) technology combines an antenna (or antennas) with a single-chip radio die into a standard surface mounted

device symbolizing an innovative and important development in the

miniaturization of wireless communications systems in recent years.

The AiP technology is now the mainstream antenna technology and

has been widely adopted by chip makers for 60 GHz radios. The slides

focus on the development of the AiP technology in low-temperature

cofired ceramic (LTCC) process for 60 GHz radios by Y. P. Zhang and

his students and collaborators.

*This use of this work is restricted solely for academic purposes. The author of this work owns the copyright and no reproduction in any form is permitted without written permission by the author.*

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Key Words

Antenna: Discrete antenna, integrat ed antenna, and AiP; Package: Wire-bond package, flip-chip package; Circuit: Discrete circuit,

integrated circuit; Chip: Packaged die, bare die; Process: LTCC,

PCB, and CMOS.

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What is AiP Technology? AiP technology is an antenna solution technology that implements an

antenna or antennas on (or in) an IC package that can carry a highly-

integrated radio or radar transceiver die (or dies).

RF Transceiver Die

Antenna

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Why AiP Technology? As compared with current chip antenna solution, AiP has better system

performance, smaller system PCB area, lower system and assembly

cost, and shorter time to market. Obviously, AiP offers an elegant

antenna solution to single-chip radio or radar transceivers.

Chip Antenna

AiP

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How AiP Technology Evolved? Inspired from the similarity between ceramic patch antenna1 and

hermetic ceramic package2, AiP5-7 evolved from used ceramic package3

through PCB mockup4.

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Who Have Created Knowledge about AiP?

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Who Have Been Recognized for AiP Technology?

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Who Else Contributed to AiP Technology?

Incomplete list of early AiP contributors

IMEC CUHK YONSEI PRC

ITRI AMKOR

FRACTUS

Insight SiP

IMST

FRACTUS

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Who Else Contributed to AiP Technology?

NEC IBM

Panasonic

Incomplete list of early AiP contributors

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Infineon

SAMSUNG

STM

IBM

Who Developing AiP Technology Right Now?

Incomplete list of current AiP developers

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IMEC

Hittite

Tensorcom

Qualcomm

Who Developing AiP Technology Right Now?

Incomplete list of current AiP developers

Panasonic NTT

Intel

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AiP Technology

AiP for Rx AiP for Tx

10 mm

It is now the mainstream antenna technology for 60 GHz.

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AiP Design

Fig. 4. Design methodology.

Codesign of antenna and package will maximize the AiP performance. Of course,

it would be much better if chip could be also included in the design flow.

Package

Antenna

3D EM

Simulation

HFSS

2D EM

Simulation

IE3D

Design

Released

Provisional

Specification

Can not meet

specification

Meet

specification Meet

specification

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AiP Fabrication

Fig. 5. LTCC Fabrication Facilities (SIMTech).

Low temperature cofired ceramic (LTCC) material and process are suitable for AiP

mass production.

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AiP Measurement

2

212

11

21221

211

1

212

SS

SSSZZ od

Fig. 6. Measurement setup (IBM).

Probe-based measurement setup is needed to measure an AiP and a balun for a

differential signal operation.

(1)

cd

cd

ZZ

ZZRL

10log20 (2)

where Zo = 50 W and Zc = 100 W.

Antenna arm

Wave guide twist

Antenna under test & probe

Motor

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Regulations for 60-GHz Radio

Realized in 1995 that

unlicensed use could be an

appropriate regime for

using such spectrum since

most of the justifications

for radio licensing were

not applicable in these

frequencies. Japan first

issued 60-GHz regulation

for unlicensed utilization

in the 60-GHz band in the

year of 2000.

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WirelessHD

ECMA

IEEE 802.15.3c

WiGig

IEEE 802.11ad

CWPAN

To encompass available but inconsistent unlicensed frequencies, the IEEE 802.15.3c

standard divides nearly 9 GHz of spectrum from 57.24-65.88 GHz into four 2.16-GHz

channels.

Supports data

transmission rates up

to 7 Gbps.

Standards for 60-GHz Radio

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Technology

Interco

nn

ect

Den

sity

Mech

an

ical

Sta

bility

Th

ermal

Co

nd

uctiv

ity

RF

Loss

An

tenn

a

Co

st

Ma

turity

Si-interposer

/Through-Si-Via

LTCC

Laminate

Laminate requires compromise / material development to provide better capability.

Si-interposers/ TSV

– Current efforts

for 3D-integration

don’t address the

needs of 60GHz.

Low temperature

co-fired ceramic

(LTCC) technology

is established for

mm-wave

applications.

Wire bonding possible and flip-chip bonding suitable for 60-GHz die attach.

Package Technology Choices for 60-GHz Radio

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1975 1980 1985 1990 1995 2000 2005 2010

Silicon

LTCC

III-V

LCP

PCB

Others

Patch Pole Yagi Slot Grid Others

Others: Silica, glass, quartz, ceramic, foam,

polymer, resin and MEMS.

Others: Lens, PIFA, IFA, cavity, horn, and

waveguide antennas.

Antenna Type Choices for 60-GHz Radio

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LTCC Electrical Mechanical Thermal Conductor

εr tanδ MPa GPa ppm/K W/mK

A6 M 5.7 0.0023 170 92 7 2 Au

ACX 7.5 0.01 NA NA 4.7 NA Cu

943 7.4 0.002 230 150 6 4.4 Ag

GL 940 18.7 0.00025 220 188 10.7 3.5 Ag

GL 950 9.4 0.0014 400 173 8.5 4.1 Ag

GL 330 7.5 0.0015 400 178 8.2 4.3 Cu

GL 570 5.6 0.0019 200 128 3.4 2.8 Cu

GL 771 5.2 0.0036 170 74 12.3 3.0 Cu

LTCC Material Properties

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E

L1

L2

J

M

Q J

B

A C

D H G

N

F

K

Inner pattern

via

W/B pads

O

Su

bstra

te edg

e

P

Items Symbol Specification

(Min in mm)

W/B pad width A 0.125

W/B pad width B 0.200

Gap between W/B pads C 0.100

Line width D 0.100

Line to part pad spacing E 0.150

Cavity to part pad spacing F 0.200

Cavity to W/B pad spacing G 0.200

Cavity to cavity spacing H 1.000

Cavity to substrate edge J 1.000

Line to line spacing K 0.100

Cavity to line (surface) L1 0.200

Cavity to line (inner) L2 0.200

Via (d) pitch or to part edge M 2d

W/B pad to line N 0.100

Conner of cavity O 0.150

W/B pad to via edge P 0.200

Via edge to cavity edge Q 0.250

LTCC Design Rules

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≥ 0.2 mm ≥ 0.15 mm

≥ 0.4 mm

= 0.25 mm = 0.55 mm

= 0.35 mm

= 0.38 mm

Au W/B pad = 0.25 mm × 0.25 mm

Au extension = 0.15 mm × 0.35 mm

Au catch pad diameter 0.25 mm

W/B pad offset = 0.25 mm

LTCC Design Rules

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Finished part dimensional tolerance is generally ± 0.7 % of part size but not less than

± 100μm for green cut parts.

The shrinkage tolerance of circuit features in x and y direction is typically less than

± 0.1 % (production ± 0.2% typically).

The minimum recommended substrate thickness is 500 μm. Layer thickness

tolerance is ± 7 % (typically < ± 2% within manufacturing lot).

The via hole punching to the tape sheet can be made typically to 10 μm accuracy

in production.

The layer-to-layer alignment accuracy for via and conductor is typically 10~20 μm.

The screen printed conductor alignment error is typically 5~10 μm.

The line width tolerance is typically 5%.

Dielectric constant of 5.9 ± 0.2, loss tangent of 0.002 ± 0.02% , and conductivity of

2.5 ×107 S/m for A6M at 60 GHz.

LTCC Tolerances

www.ltcc.de

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Conductor roughness

• Increase in conductor loss more than 2 times (experimentally demonstrated).

• Affects effective permittivity.

• Affects phase constant especially in thinner substrates

Ceramic roughness

• Affects thickness (so impedance).

• Affects effective permittivity.

LTCC Roughness

www.ltcc.de

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Array-Antenna-in-Package Design for Highly-Integrated 60-GHz Radio

Microstrip Patch Array Antenna

Major advantages: Low profile, conformable to planar and non-planar surfaces, easy

to design, simple to manufacture, compatible with both single-ended and differential

silicon radio.

Major disadvantages: Low efficiency, high Q, poor polarization purity, spurious feed

radiation and very narrow impedance bandwidth.

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LTCC Microstrip Patch Array Antenna

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Microstrip Grid Array Antenna

It was invented by Kraus in 1964, revived by Conti, et al in 1981, and studied by

Nakano, et al at lower microwave frequencies.

Major structural advantages: Low profile, conformable to planar and non-planar

surfaces, easy to design, simple to manufacture, simple feeding network, compatible

with both single-ended and differential silicon radio.

Major operational advantages: High efficiency, high gain, good polarization purity,

wide impedance and gain bandwidth, can be travelling-wave and able to beam steering

by frequency shift, can be resonant with boresight beam radiation.

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Microstrip Grid Array Antenna Design Guidelines and Examples

Choice of substrate: A thick substrate means using a low dielectric

constant to limit the generation of surface waves.

Number of loops: Given the specified gain G, the number of loops can

be estimated by 2×10(G-Gd)/10 where Gd is the gain of microstrip half-

wave dipole.

Loop short side design: A short side is a radiating element. The

length is required to be λg/2 for resonance. The width sets the

radiation resistance, which is governed by the desired amplitude taper

on the array.

Loop long side design: A long sideis a transmission line. The length is

required to be λg for resonance. The width sets the characteristic

impedance, which should match the short side impedance.

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LTCC Microstrip Grid Array Antenna Design Example 1

xv

yv

l

w

dv

da

Single Feed Design

Number of meshes 14

Mesh dimensions l = 2.5 mm ≈ λg, w = 1.365 mm ≈ λg/2

Substrate dimensions 13.5mm×8mm×0.375 mm

Line width and thickness 0.15mm and 0.01 mm

Excitation location xv = 7.3 mm, yv = 3.98 mm

Feeding dimensions dv= 0.1 mm, da = 0.3mm

Specifications @ 60 GHz in Ferro LTCC A6M

Bandwidth = 7 GHz, efficiency > 80%, and maximum

gain = 15 dBi

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Frequency (GHz)

51 53 55 57 59 61 63 65 67 69

mag

(S11

) (d

B)

-25

-20

-15

-10

-5

0

Frequency (GHz)

50 52 54 56 58 60 62 64 66 68 70

Peak

Rea

lized

Gai

n (d

Bi)

0

5

10

15

20

Simulations show that large impedance bandwidth of 13 GHz (21.4% @ 61.5 GHz),

maximum gain of 15 dBi, and 3-dB gain bandwidth of 10 GHz are achieved.

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-40dB

-30dB

-20dB

-10dB

0dB0

30

60

90

120

150

180

210

240

270

300

330

Co

Cross

= 0

z

x-40dB

-30dB

-20dB

-10dB

0dB0

30

60

90

120

150

180

210

240

270

300

330

Co

Cross

= 0

z

y

y

z

x

Simulations show that desirable patterns with low side lobe and week cross-polarization

radiation are achieved.

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An excellent matching to a 50-Ω source achieved from 56.3-65 GHz. The measured

and calculated peak gain values are both 14.5 dBi with estimated efficiency better

than 95% at 60-GHz. No de-embedding was made between the post-layout

simulation and measurement.

Frequency (GHz)55 56 57 58 59 60 61 62 63 64 65

mag

(S1

1)

(dB

)

-35

-30

-25

-20

-15

-10

-5

0Measured

Simulated

Frequency (GHz)55 56 57 58 59 60 61 62 63 64 65

Pea

k g

ain

(d

Bi)

-5

0

5

10

15

20

25

Eff

icie

ncy

.6

.7

.8

.9

1.0

Measured gain

Simulated gain

Simulated efficiency

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-40dB

-30dB

-20dB

-10dB

0dB0

30

60

90

120

150

180

210

240

270

300

330

Measured, Co

Measured, Cross

Simulated, Co

Simulated, Cross

= 0

z

x-40dB

-30dB

-20dB

-10dB

0dB0

30

60

90

120

150

180

210

240

270

300

330

Measured, Co

Measured, Cross

Simulated, Co

Simulated, Cross

= 0

z

y

60 GHz


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xv1

yv

l

w

dv

da

Dual Feed Design

Number of meshes 14

Mesh dimensions l = 2.5 mm ≈ λg, w = 1.365 mm ≈ λg/2

Substrate dimensions 13.5mm×8mm×0.375 mm

Line width and thickness 0.15mm and 0.01 mm

Excitation location xv1 = 4.57 mm, xv2 = 3.5 mm,

yv = 3.98 mm

Feeding dimensions dv= 0.1 mm, da = 0.3mm


Bandwidth = 7 GHz, efficiency > 80%, and maximum

gain = 15 dBi

xv2

yv

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Simulations show that large impedance bandwidth of 10 GHz (16.3% @ 61.5 GHz)

and maximum gain of 14 dBi for single-ended excitation and of 8 GHz (13% @ 61.5

GHz) maximum gain of 16 dBi for differential excitation are achieved, respectively.

Frequency (GHz)50 52 54 56 58 60 62 64 66 68 70

Ret

urn

lo

ss (

dB

)

0

5

10

15

20

25

30

35

diff

single

Frequency (GHz)50 52 54 56 58 60 62 64 66 68 70

Pea

k r

eali

zed

gai

n

(dB

i)

0

5

10

15

20

diff

single

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Simulations show that differential excitation has narrower beamwidth in the E plane

and similar beamwidth in the H plane than those of single-ended excitation.

-40dB

-30dB

-20dB

-10dB

0dB

0

30

60

90

120

150

180

210

240

270

300

330

co, diff

cross, diff

co, single

cross, single

= 0

z

x-40dB

-30dB

-20dB

-10dB

0dB

0

30

60

90

120

150

180

210

240

270

300

330

co, diff

cross, diff

co, single

cross, single

= 0

z

x

y

z

x

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Solder balls

PCB cavity

M1 M2 M3 M4

60-GHz radio diePCB board

Vd- Vd+ Vs

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Frequency (GHz)55 56 57 58 59 60 61 62 63 64 65

Ret

urn

lo

ss

(dB

)

0

5

10

15

20

25

30

35

Measured

Simulated

Frequency (GHz)55 56 57 58 59 60 61 62 63 64 65

Pea

k r

eali

zed

gai

n

(dB

i)

-5

0

5

10

15

20

25

Eff

icie

ncy

.6

.7

.8

.9

1.0

Measured peak realized gain

Simulated peak realized gain

Simulated efficiency

An excellent matching to a 50-Ω source achieved from 56.3-63.2 GHz. The

measured and calculated peak realized gain values agree well with estimated

efficiency better than 95% at 60-GHz. No de-embedding was made between the

post-layout simulation and measurement.

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-40dB

-30dB

-20dB

-10dB

0dB0

30

60

90

120

150

180

210

240

270

300

330= 0

z

x-40dB

-30dB

-20dB

-10dB

0dB0

30

60

90

120

150

180

210

240

270

300

330= 0

z

x

60 GHz

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1

3 4

5 2


Bandwidth = 7 GHz, efficiency > 80%, and gain

≥ 15 dBi over 7-GHz

Number of meshes 32

Substrate dimensions 15mm×15mm×0.5 mm

Linearly polarized

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50 52 54 56 58 60 62 64 66 68 70-55

-50

-45

-40

-35

-30

-25

-20

-15

-10

-5

0

|S1

1| (d

B)

Frequency (GHz)

Pre simulation without signal traces

Measured without signal traces

Measured with signal traces

Post simulation without signal traces

50 52 54 56 58 60 62 64 66 68 70-10

-8

-6

-4

-2

0

2

4

6

8

10

12

14

16

18

Pea

k r

eali

zed

ga

in (

dB

i)

Frequency (GHz)

Pre simulation without signal traces

Measured without signal traces

Measured with signal traces

Post simulation wihout signal traces

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LTCC Microstrip Grid Array Antenna Design Example 3 60 GHz

(a) (b)60 GHz

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Concluding Remarks

The AiP technology originated from Zhang’s work has emerged as the most

elegant antenna solution to modern radio systems.

The AiP technology has been demonstrated for WLAN, UWB, and millimeter-

wave (60 GHz) radios, respectively.

The AiP technology combines an antenna (or antennas) with a single-chip radio

die into a standard surface mounted device symbolizing an innovative and

important development in the miniaturization of wireless communications

systems in recent years.

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Acknowledgement

Zhang would like to acknowledge the contribution from his former students:

Mr. Xue Yang, Mr. Lin Wei, Dr. Wang Junjun, Dr. Sun Mei, Dr. Zhang Bing and

from his collaborators: Mr. Chua Kai Meng, Ms. Wai Lai Lai, and Dr. Albert Lu

Chee Wai from Singapore Institute of Manufacturing Technology, Dr. Liu Duixian

and Mr. Brain P. Gaucher from IBM T. J. Watson Research Center, USA , and

Prof. C. Luxey, Dr D. Titz, and Dr. F. Ferrero from Université Nice Sophia-

Antipolis , France in the development of AiP technology.

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References

Y. P. Zhang, “Integrated circuit ceramic ball grid array package antenna,” IEEE Transactions on

Antennas and Propagation, Vol. 52, No. 10, pp. 2538-2544, October 2004.

Y. P. Zhang, M. Sun, W. Lin, “Novel antenna-in-package design in LTCC for single-chip RF

transceivers,” IEEE Transactions on Antennas and Propagation, vol. 56, no. 7, pp. 2079-2088,

July 2008

Y. P. Zhang, “Enrichment of package antenna approach with dual feeds, guard ring, and fences of

vias,” IEEE Transactions on Advanced Packaging, vol. 32, no. 3, pp. 612-618, August 2009.

Y. P. Zhang, D. Liu, “Antenna-on-chip and antenna-in-package solutions to highly-integrated

millimeter-wave devices for wireless communications,” IEEE Transactions on Antennas and

Propagation, vol. 57, no. 10, pp. 2830-2841, October 2009.

Y. P. Zhang, M. Sun, K. M. Chua, L. L. Wai, D. Liu, “Antenna-in-package design for wirebond

interconnection to highly-integrated 60-GHz radios,” IEEE Transactions on Antennas and

Propagation, vol. 57, no. 10, pp. 2842-2852, October 2009.

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References

Y. P. Zhang, M. Sun, D. Liu, Y. L. Lu, “Dual grid array antennas in a thin-profile package for flip-

chip interconnection to highly-integrated 60-GHz radios,” IEEE Transactions on Antennas and

Propagation, vol. 59, no. 4, pp. 1191-1199, April 2011.

D. Liu, Y. P. Zhang, “Integration of array antenna in chip package for 60-GHz radios,”

Proceedings of the IEEE, vol. 100, no. 7, pp. 2364-2371, July 2012

B. Zhang, Y. P. Zhang, D. Titz, F. Ferrero, C Luxey, “A circularly-polarized array antenna using

linearly-polarized sub grid arrays for highly-integrated 60-GHz radio,” IEEE Transactions on

Antennas and Propagation, vol. 61, no. 1, pp. 436-439, January 2013.

B. Zhang, D. Titz, F. Ferrero, C Luxey, Y. P. Zhang, “Integration of quadruple linearly-polarized

microstrip grid array antennas for 60-GHz antenna-in-package application,” IEEE Transactions on

Components, Packaging and Manufacturing Technology, vol. 3, no. 8, pp. 1293-1300, August

2013.

W. M. Zhang, Y. P. Zhang, M. Sun, C. Luxey, D. Titz, F. Ferrero, “A 60-GHz circularly-polarized

array antenna-in-package in LTCC technology,” IEEE Transactions on Antennas and Propagation,

vol. 61, no. 12, pp. 6228-6232, December 2013.

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Biography

Y. P. ZHANG is a Professor of Electronic Engineering with the

School of Electrical and Electronic Engineering at Nanyang

Technological University, Singapore. He serves as an Associate

Editor of the IEEE Transactions on Antennas and Propagation. He

received the S. A. Schelkunoff Transactions Prize Paper Award of

the IEEE Antennas and Propagation Society (2012). He was the

Chair, leading the Singapore Chapter to win the Best Chapter Award

of the IEEE Antennas and Propagation Society (2013). He was the

Advisor, guiding the Singapore Chapter to win the Outstanding

Chapter Award of the IEEE Microwave Theory and Technique

Society

(2014). He was elevated as a Fellow of IEEE in 2009 for his

contributions in subsurface radio and integrated antenna.

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Antenna Boy

Questions and Comments to [email protected]

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