| This thesis investigates techniques to reduce the insertion loss for high gain antenna arrays and comparison of the feed elements. Moreover, the research investigates techniques to reduce the insertion loss in microstrip feed network and optimization of the feed elements at 30 GHz.;Several microstrip lines, microstrip bends, power dividers, impedance transformers, and feed techniques were designed, simulated, optimized, fabricated and measured on a vector network analyzer for analysis.;The results of the investigation are then applied to a feed network design for a 16 element Fresnel lens array that has been designed, fabricated, and characterized by research scientist and engineers from the Communications Research Centre Canada, located in Ottawa. This array was selected because it is representative of current state-of-the-art performance of planar high gain antennas.;The second part of the research investigates alternate low-gain antenna elements that can be used as feed elements in the 16 element Fresnel lens array. A slot antenna and a dielectric resonant antenna were designed, simulated, fabricated, and measured in order to compare their performance to the aperture-coupled patch antenna that is used in the existing corporate feed network for the 16-element Fresnel lens array.;The first part of the research concentrates on techniques to reduce the insertion loss due to bends, power dividers, impedance transformers and three different feed network techniques; series feed, corporate feed, and a hybrid corporate-series feed.;The aperture-coupled patch antenna, aperture antenna, aperture antenna with reflector, and a DRA were designed, simulated, and characterized inside an anechoic chamber for analysis and comparison.;The research led to a new hybrid corporate-series microstrip feed network design that resulted in a more than 3 dB improvement in the insertion when compared to the original corporate feed network for the 16-element Fresnel lens array.;In addition, the research has shown that the DRA is as good a candidate as the aperture-coupled patch antenna to feed the Fresnel lens array. The radiation pattern of the DRA is slightly larger than the aperture-coupled patch antenna, allowing for the Fresnel lenses to be re-designed with a smaller focal length-to-diameter (F/D) ratio, such that the array could be lowered on to the radiating elements, thus achieving an antenna array with a smaller profile.;As well, it has been shown that the finite element method-based commercial software is quite accurate in simulating a Fresnel lens, microstrip structures, and antenna elements at 30 GHz. |
