Miniaturization and Gain Enhancement of Wideband Low-profile Antennas on

Engineered Structures

Presented by -

Faisal Abedin (Doctoral Candidate)

Department of Electrical Engineering

University of South Carolina, Columbia, SC 29208

E-mail: abedin@engr.sc.edu

Advisor: Dr. Mohammod Ali

Education

Doctoral Candidate (GPA: 3.92) Major: Electrical Engineering (Start Date: Spring 2003) Department of Electrical Engineering University of South Carolina, Columbia, SC

M.S. in Electrical Engineering, May 2001 Department of Electrical and Computer Engineering North Carolina State University, Raleigh, NC

B.S. in Electrical Engineering, September 1999 Department of Electrical Engineering Bangladesh University of Engineering and Technology, Dhaka, Bangladesh

Research Interest

Electromagnetic Band-gap (EBG) Structures and their Antenna Applications

Antenna miniaturization Diversity antennas

Biography

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Outline

3

Introduction

Novel concept to design ultra-thin Mobile Phone Antennas

Introduction to Engineered Structures called Electromagnetic

Bandgap (EBG) structures

Three-dimensional EBG structures

Planar EBG structures

Phase profile of EBG structures

Application of Planar EBG structures

Introduction

3

Personal Communication

Systems

Mobile Data System

GPS

Commercial & Defense Applications

UAV

Satellite

Dual band antenna on Modified ground plane

Novel Design Concept for Mobile Antennas

Dual band antenna on Conventional ground plane

Application: Mobile Antennas

Printed internal antenna

Cell phone back cover

Proposed a Novel Slow-wave Structure

90 mm

35 mm

h=10 mm

Feed

Metal Ground

Antenna

Ground90 mm

h=4 mm

FeedGround

Metal Gap Antenna

4

Novel Design Concept for Mobile Antennas

M. F. Abedin and M. Ali, “Modifying the Ground Plane and its Effect on Planar Inverted-F Antennas (PIFAs) for Mobile Phone Handsets,’’ IEEE Antennas and Wireless Propagation Letters, vol.2, no. 15, pp. 226-229, 2003.

Antenna prototype

Accomplishments Increases the antenna electrical length by uniformly spreading current

Increases the antenna bandwidth by 3 to 4 times

Reduces the antenna height by 2.5 times

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Current Distribution

Conventional Antenna

Proposed Antenna

Higher Current Density

Maximum Current

Minimum Current

Antenna Miniaturization using Engineered Structures

Applications of Dipole Antenna Array

Ground-based

Vehicular

Air-borne applications

Z

X

height ≈ 0.25 wavelength

Array of Dipole Antennas

Dielectric substrate

Metal Ground

Conventional Dipole Array Configuration

UAV

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Antenna Miniaturization using Engineered Structures

Thin antenna structure Light-weight and compact Directional Wideband

Dipole Antenna

h= 0.01 wavelength

Engineered Structure (EBG)

Goals

Challenges

Generates surface wave

Costly Increases Radar Cross-section

Reduces antenna efficiency

Requires 0.25 wavelength height

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Metal plates

Dipole Antenna

Metal Ground

Proposed Solution

Phase Profile of EBG Structures

Antenna Miniaturization using Engineered Structures

Ph

ase

(Deg

rees

)

Frequency (GHz)

Metal Ground

EBG Surface

Phase profile

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h << λ/4

In phase

Engineered Structure

h < λ/4

Out of phase

Dielectric Substrate

Antenna

In phase

h =

λ/4

Direct wave

Reflected wave

Metal Ground

M. F. Abedin and M. Ali, “Effects of EBG Reflection Phase Profiles on the Input Impedance and Bandwidth of Ultra-thin Directional Dipoles,’’ IEEE Transactions on Antennas and Propagation (under revision).

EBG Top View

Dipole Antenna Balun circuitry

Coaxial cable

Accomplishments Reduced antenna height by 9 times

Attained sufficient antenna bandwidth

Increased antenna Gain and Efficiency

Antenna Miniaturization using Engineered Structures

Dipole Antenna Performance on Proposed EBG Structure

2.8 mm ≡ 0.03λ

Metal PlatesDipole Antenna

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Ref

lect

ion

(d

ecib

els)

Novel Planar EBG Structures

Applications: Planar EBG

▪ Mobile phones ▪ Wireless LAN ▪ Satellite ▪ JTRS ▪ Global Positioning System

Stopband3.5 – 4.5 GHz

Top-view

Advantages: Planar EBG

▪ Extremely low cost

▪ Easy to fabricate

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Unit cell of proposed Planar EBG Structure

Tra

nsm

iss

ion

(d

ecib

els)

Application of Planar EBG Structures

d = 51 mm

Dielectric Substrate

Dipole Antennas

EBG Structure

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Coupling reduced by 13 dB

Mu

tual

Co

up

lin

g (

dec

ibel

s)

Application of Planar EBG Structures

M. F. Abedin and M. Ali, “Application of EBG Structures to Reduce the Mutual Coupling between Linear Antenna Elements of an Array,’’ IEEE Antennas and Wireless Propagation Letters (submitted March 2005).

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Without EBG

Null Points – No Signal

With EBGNulls

Eliminated

Accomplishments Increased bandwidth by 31%

Reduced coupling by 13 dB

Eliminated Nulls in Radiation Pattern

Increased antenna Gain

Broader Dissemination

Actively involved in disseminating knowledge to the broader community –

Mentored two High School Seniors through SPRI program in previous years

This summer an 11th Grade student will be mentored to conduct research

An undergraduate EE student of USC will be guided this summer funded through an NSF REU grant

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Relevant Publications

1. M. F. Abedin and M. Ali, “Modifying the Ground Plane and its Effect on Planar Inverted-F Antennas (PIFAs) for Mobile Phone Handsets,’’ IEEE Antennas and Wireless Propagation Letters, vol. 2, no. 15, pp. 226-229, 2003.

2. M. F. Abedin and M. Ali, “Effects of EBG Reflection Phase Profiles on the Input Impedance and Bandwidth of Ultra-thin Directional Dipoles,’’ IEEE Transactions on Antennas Propagation (under revision).

3. M. F. Abedin and M. Ali, “Application of EBG Structures to Reduce the Mutual Coupling between Linear Antenna Elements of an Array,’’ IEEE Antennas and Wireless Propagation Letters (submitted).

4. M. Ali and M. F. Abedin, “Designing Ultra-Thin Planar Inverted-F Antennas,” in Proc. IEEE Antennas and Propagation Society International Symposium Digest, vol. 3, pp. 78-81, Columbus, OH, June 2003.

5. M. F. Abedin and M. Ali, “Application of EBG Substrates to Design Ultra-Thin Wideband Directional Dipoles,’’ in Proc. IEEE Antennas and Propagation Society International Symposium, vol. 2, pp. 2071-2074, Monterey, CA, June 2004.

6. M. F. Abedin and M. Ali, “Designing Ultra-Thin Printed Dipole Arrays based on EBG Reflection Phase Profile,” IEEE Wireless and Microwave Technology (WAMI) Conference 2005, Clearwater, FL, April 2005 (accepted).

7. M. F. Abedin and M. Ali, “Reducing the Mutual-Coupling between the Elements of a Printed Dipole Array Using Planar EBG Structures,” IEEE Antennas and Propagation Society International Symposium, Washington, DC, July 2005 (submitted).

8. M. F. Abedin, M. Ali and P. F. Wahid, “Bandwidth, Efficiency and Pattern Characteristics of Miniaturized Embedded Antennas at 900/1900 MHz,” 9th edition of the Biennial International Conference on Electromagnetics in Advanced Applications.(ICEAA 2005), Torino, Italy, September 2005 (under preparation).

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