Graduation Year

2007

Document Type

Thesis

Degree

M.S.E.E.

Degree Granting Department

Electrical Engineering

Major Professor

Elias Stefanakos, Ph.D.

Co-Major Professor

Kenneth A. Buckle, Ph.D.

Keywords

Microstrip slot antenna, Schottky diode, Detector, Coplanar waveguide (CPW), Wideband, W band, Membrane

Abstract

This thesis presents the rectifying antenna potential for infrared and millimeter wave energy conversion. Infrared imaging is one of the emerging technologies that have attracted considerable attention in the next generation of military, medical, and commercial applications. Moreover, with the ever-increasing congestion of the electromagnetic spectrum at RF and microwave frequencies and the establishment of firm civilian and military requirements best met by millimeter wave systems, the interest in the technology has grown and is now firmly established. During this work a 2.5GHz slot antenna, a 2.5GHz Schottky diode detector, a CPW-to-Microstrip transition, a fully integrated Rectenna element, and a 94GHz slot antenna were designed, fabricated, and tested. Results on the performance of the devices show a great deal of correlation between the simulated and measured data.

To perform an initial study, the CPW-fed narrow slot antenna is designed at 2.5GHz and implemented on an FR-4 board. This investigation serves as the basis for the development of the Rectenna element at millimeter wave frequencies. In order to increase the bandwidth of the slot antenna, a 2.5GHz CPW-fed wide slot antenna with U-shaped tuning stub is realized, which provides a 60% increase in bandwidth while keeping the same radiation characteristics. In addition, a set of simulations is performed to show how a reflector plate affects the radiating properties of the slot antenna. A 2.5GHz square-law detector is also designed, fabricated, and tested in order to rectify the RF signal delivered by the antenna. The fabricated detector presents a well matched condition at the design frequency with a dynamic range found to be from --17dBm to --50dBm. The low frequency Rectenna element prototype is then integrated within a single FR-4 board.

This is accomplished by implementing a compact via-less CPW-to-Microstrip transition. Finally, a 94GHz CPW-fed wide slot antenna is realized on a 10μm high resistivity silicon membrane. This antenna shows a great deal of similarity to the 2.5GHz slot antenna. This low profile antenna presents at least a 10dB return loss over the entire W band frequency window. Simulated antenna efficiencies of up to 99% were achieved assuming a perfect conductor.

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