Thesis Abstracts 2001
Research and Graduate Studies Electrical and Computer Engineering
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Dielectric Resonator Antenna (DRA)
By: Capt J.P.S. McKenzie, B.Sc.
Supervisors: Dr. Yahia Antar and Dr Aldo Petosa (CRC Ottawa)
Abstract
The continuing growth in demand for wireless communications and advanced radar applications has pushed industry to develop new and better systems. Many of these systems are designed to operate at EHF band frequencies to take advantage of benefits such as reduction in equipment size and wider bandwidth. These systems require new hardware solutions to overcome the difficulties encountered when operating at very high frequency. One technology that has recently been proposed for use in the antenna portion of EHF systems is the dielectric resonator antenna (DRA). DRAs offer advantages such as low cost, ease of manufacture, wider bandwidth, and high radiation efficiency.
This thesis presents an examination of DRAs operated at EHF band frequencies. The use of coplanar waveguide (CPW) as the feeding transmission line medium is also investigated. CPW have found increasing use in EHF systems due to their simple structure that requires only one metallic layer and their potential for wide bandwidth and low loss performance. Both single element and antenna arrays were examined to determine the suitability of DRAs for a wide range of EHF applications. Detailed analysis and characterization of the DRA element, coupling slot, tuning mechanism, and CPW feed line was conducted. Antenna parameters such as element size and permittivity as well as coupling slot shape and dimension were examined in detail using CAD software. Based on these results a number of prototype antennas and arrays were fabricated and tested. Difficulties in launching the input signal onto the CPW lines encountered during testing necessitated the design of a novel MS-to-CPW transition. The transition was designed using commercial software and was tested experimentally, demonstrating S21 better than -3 dB over the frequency range of 30.925 to 32.00 GHz, or 3.4 % relative bandwidth, while demonstrating S11< -20 dB over the same range.
The antenna prototypes were also measured and agreement between measured and simulated results in terms of resonant frequency was good. Measured –10 dB bandwidth was 2.54% which is less than predicted by simulation. This reduction is due to the inclusion of the MS-to-CPW transition, which was not modeled in the simulated antenna structure. The single element DRA integrated with the transition demonstrated a maximum gain of 4.63 dB in the E-plane at 31.4 GHz and a radiation pattern consistent with simulation results. This thesis demonstrates that DRAs fed by CPW have potential for use in EHF systems and the performance obtained for the antennas presented here compares well with previously reported antennas of similar type.
