Abstract
The work of this project entitled “Travelling-Wave Feed Technique for Circularly Polarized Patch Array” was to investigate the feasibility of replacing conventional planar antenna feed technique with a feed channel in the ground plane beneath microstrip rectangular patch elements. In particular, a novel strategy, using travelling-wave coupling, was explored that provided efficient feeding of a travelling-wave antenna, with the ability to electronically change the hand of polarization. It involved the analysis of the electromagnetic coupling between conducting layers in a multilayer structure and the subsequent development of circuit design rules. The work has led to the generation of design techniques that are suitable for printed thick film or low temperature co-fired ceramic (LTCC) multilayer structures. The new feed technique was demonstrated through measurements on five circularly polarized patch arrays with travelling-wave feeds. Antennas were designed and measured at 5 GHz and 15 GHz, using PTFE, LTCC and thick film materials to demonstrate the validity of the new technique. The first part of the research studied the feasibility of employing four travelling-wave fed linearly polarized rectangular patches to provide a circularly polarized patch array. This led to the development of an eight-patch antenna array with different incremental offsets between the patches and the travelling-wave feed channel beneath the patches. Multilayer LTCC and printed thick film technology were the focus of the second part of this research, which concentrated on realising compact microwave patch arrays with enhanced radiation characteristics. These included a 15 GHz multilayer LTCC compact patch array, as well as a 5 GHz multilayer array fabricated using printed thick film. Finally, a linearly polarized patch antenna with a unique arrangement of low dielectric constant material, for enhanced radiation, was investigated.