[Air Bubbles Free Artificial Dielectric Material Fabrication in Specified Molds for Ultra Wide Band Antenna Miniaturization]

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ACKNOWLEDGEMENT

I would take this opportunity to thank my research supervisor, family and friends for their support and guidance without which this research would not have been possible.

DECLARATION

I, [type your full first names and surname here], declare that the contents of this dissertation/thesis represent my own unaided work, and that the dissertation/thesis has not previously been submitted for academic examination towards any qualification. Furthermore, it represents my own opinions and not necessarily those of the University.

Signed __________________ Date _________________

TABLE OF CONTENTS

ACKNOWLEDGEMENTII

DECLARATIONIII

CHAPTER 1: INTRODUCTION1

Current MEMS Antennas1

Mechanically Actuated Antennas3

Pattern Reconfigurable Antennas3

Capacitive MEMS Antenna5

MEMS Phased Array5

Significance of the MEMS Actuated Broadband Antenna6

Fabrication (HiDE C) Facilities6

Materials7

Computational Simulator Ansoft HFSS8

Post Processing Detection Algorithm9

Applications for MEMS Broadband Antenna9

CHAPTER 2: LITERATURE REVIEW11

Device Design11

MEMS Platform Design12

Challenges with Preliminary MEMS Platform Design13

Final Platform Design13

Active Microwave Sensors (Radars)15

Polarization17

SAR interferometry19

Fabrication Overview25

Antenna Structure26

Antennas and their classification28

Radiation patterns for directional antennas31

Antenna modes of directional antennas32

Impact of directionality33

Artificial Magnetic Materials35

CHAPTER 3: COMPOSITE ARTIFICIAL MATERIAL FABRICATION38

Material Fabrication38

Sylgard® 184 Composites38

Mold Design40

Mold Design Requirements40

Mold Design and Use41

Some Unsuccessful Molds Design47

REFERENCES52

CHAPTER 1: INTRODUCTION

The goal of this work was to integrate a broadband antenna into a micro-electrical-mechanical systems (MEMS) rotatable platform. MEMS devices are inherently multidisciplinary as they can incorporate aspects of electrical, mechanical, optical, chemical and biological engineering to create a device which capitalizes on elements of each of the fields. The nature of the work presented in this dissertation was a multidisciplinary blend of electromagnetics and mechanical engineering. The antenna and the MEMS platform each had requirements that were jointly considered to design and fabricate a device that did not compromise the performance of either aspect.

The arrangement of this dissertation will reflect this multidisciplinary approach and detail both the mechanical and electromagnetic design, fabrication and testing aspects of the broadband MEMS antenna.

Current MEMS Antennas

The development of the first directional antenna drove researchers to try many different methods to control the shape and orientation of the antenna beam. Initially, antennas were physically manipulated to achieve the required beam steering. The natural evolution was to utilize machinery to control the movement allowing greater precision and ease-of-use. Gimbal systems comprised of a series of concentric rings were used to point the antenna in any desired direction. Antenna arrays were the next development in which users controlled the excitement phase which allowed electronic steering of the beam. The phased array system required complex feeding networks but was able to scan at a fast rate. These phased arrays often included expensive ferrite or solid-state phase shifters and/or software controlled beam forming networks. These systems were complicated, cost-prohibitive, lossy, and had a large footprint which led to them being utilized in only a few sophisticated military and space systems. Phased arrays have achieved much greater acceptance as research has progressed, but the need for a complex feeding network and the dependence on narrowband components provides a fundamental limitation. As Micro-Electro-Mechanical Systems (MEMS) technology advances, however, a fundamental shift back to early principles of mechanical beam steering can be achieved ...