| The feasibility of a novel scanning antenna at millimeter wave frequencies is investigated in this dissertation. A unique combination of an aperture-coupled microstrip patch array, a dielectric waveguide feed line, and a mechanically variable phase shifter applied to the dielectric feed line is studied. The investigation of the aperture-coupled microstrip antenna array fed by the dielectric guide is based on a rigorous analysis of the dielectric guide, a design of the millimeter-wave microstrip antenna array and a study of the aperture coupling between the dielectric guide and the microstrip line. The hybrid mode matching technique is used to analyze the propagation constants in the dielectric guide. The propagation constants in the dielectric guide are determined with a calculation accuracy of better than 1%. The millimeter-wave microstrip antenna array fed by a parallel series microstrip network is discussed. The radiation patterns, gain, beamwidth and sidelobe level for planar antenna arrays designed at 24.725 GHz, 60.5 GHz and 76.5 GHz are measured and discussed. The frequency dependence and temperature characteristics of the planar microstrip antenna array are also presented. The coupling between the dielectric guide and the microstrip line is studied with respect to small aperture coupling theory. The numerical results obtained from this method are in good agreement with the experimental results. The scanning ability of a Ka-band 4 x 6 microstrip antenna array fed by a dielectric waveguide is successfully demonstrated in this dissertation and a 30 degree beam scanning angle is achieved. |
