Date of Award:

8-2013

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Electrical and Computer Engineering

Committee Chair(s)

Bedri A. Cetiner

Committee

Bedri A. Cetiner

Committee

Jacob Gunther

Committee

Reyhan Baktur

Committee

Edmund Spencer

Committee

T. -C. Shen

Abstract

The properties of conventional antennas are fixed by the initial design and cannot be changed. A reconfigurable antenna, on the other hand, can dynamically change its properties, and it can adjust its behavior for a given propagation condition. This dissertation work concentrates on novel reconfiguration technologies, including design, microfabrication, and characterization aspects with an emphasis on their applications to multifunctional reconfigurable antennas. In the literature, reconfigurable antennas have made use of various reconfiguration techniques. The most common techniques utilized revolved around switching mechanisms. Other techniques such as the incorporation of variable capacitors, varactors, and physical structure manipulation surfaced recently to overcome many problems faced in using switches and their biasing. Usage of fluids (microfluidic or otherwise) in antennas provides a conceptually easy reconfiguration mechanism in the aspect of physical alteration. However, a requirement of pumps, valves, etc. for liquid transportation makes the antenna implementations rather impractical for the real-life scenarios. This work reports on experiments conducted to evaluate the electrowetting on dielectric (EWOD) driven digital microfluidics as a reconfiguration mechanism for antennas. EWOD is direct manipulation technique of liquids with electrostatic actuation. There are three approaches developed for the designing these new type antennas. The first approach is based on the unique metamaterial transmission line structures which are leading to antenna miniaturization. The following methodology is based on antenna integration with a microfluidic chip which consists of an EWOD platform having a mercury droplet within it. The third methodology proposes a tunable component using superhydrophobic micro-structured surfaces. These surfaces, along with tunable wetting techniques, can be used for transition from the superhydrophobic Cassie state to the normal Wenzel wetting state to build a variable capacitive device (analog varactor, a switched capacitor) or a low-loss switch. Results are demonstrated by simulations and measurements from the fabricated prototypes.

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