Keywords

Adaptive, Antennas, Reconfigurable, Wireless communication

Abstract

Modern radar and communication systems have experienced a tremendous increase in the number of antennas onboard, on the ground, and in orbital space. This places a burden due to the confined volume and limited weight requirements especially in space applications. The reconfigurable antenna is a promising and exciting new type of antenna, where through the use of appropriate switches the antenna can be structurally reconfigured, to maintain the elements near their resonant dimensions for several frequency bands. This increases the bandwidth of the antenna dramatically, which enables the use of one antenna for several applications. Four novel reconfigurable antenna elements were designed to work at 2.45 GHz and at 5.78 GHz, to cover the transition period when wireless communication will shift to the 5.78 GHz band. The four elements designed are: the reconfigurable Yagi, the reconfigurable corner-fed triangular loop antenna, the reconfigurable center-fed equilateral triangular loop antenna and the reconfigurable rectangular-spiral antenna. None of these antennas have been reported in the literature. Simulation results for all four antennas were obtained using IE3D. Fabrication and measurements for the Yagi antenna was done and the measured results agree with simulations. All four antennas have very good performance with respect to the 3dB beamwidth and directivity. However the reconfigurable rectangular-spiral antenna is the most compact in size among all four antennas. It is (20 mm x 20 mm) in size. At 2.45 GHz it has a 3dB beamwidth of 87° and directivity of 6.47dB. As for the 5.78GHz frequency the 3dB beamwidth is 82.5° and the directivity is 7.16dB. This dissertation also introduces the use of reconfigurable antenna elements in adaptive arrays. An adaptive array that can null interference and direct its main lobe to the desired signal while being reconfigurable to maintain functionality at several frequency bands has the potential to revolutionize wireless communications in the future. Through several examples, at both the design frequencies, it is shown that the reconfigurable and adaptive antenna arrays are successful in nulling noises incident on the array. These examples illustrate how reconfigurable elements and adaptive arrays can be combined very beneficially for use in wireless communication systems.

Notes

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Graduation Date

2004

Semester

Spring

Advisor

Wahid, Parveen

Degree

Doctor of Philosophy (Ph.D.)

College

College of Engineering and Computer Science

Department

Electrical Engineering and Computer Science

Degree Program

Electrical Engineering and Computer Science

Format

application/pdf

Identifier

CFE0000003

URL

http://purl.fcla.edu/fcla/etd/CFE0000003

Language

English

Release Date

July 2005

Length of Campus-only Access

None

Access Status

Doctoral Dissertation (Open Access)

Subjects

Dissertations, Academic -- Engineering and Computer Science; Engineering and Computer Science -- Dissertations, Academic

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Engineering Commons

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