| Summary: | 碩士 === 國立彰化師範大學 === 電子工程學系 === 93 === In this thesis, the structure of a microstrip patch antenna fed by a circular waveguide is studied. The waveguide is excited by an inserted cylindrical probe extended from an SMA connector. One end of the waveguide near to the SMA is sealed by inserting a movable copper rod which functions as a tuning-short. Moving the copper rod to an appropriate position can match the impedance of the circular waveguide to that of the SMA. The waveguide couples the energy to the microstrip patch through a narrow slot deposited on the open end of the waveguide. The metal plate surrounding the slot together with the waveguide flange serves as the ground plane for the microstriop patch antenna structure. The foam substrate of various thickness is laid on the ground plane to support the radiating patch. Extensive experiments have been carried out in this study to find the accurate dimensions of the antenna structure. The commercial software package ‘HFSS’ is used to simulate the antenna performance before the experiments. The current distributions of the patch at resonant frequencies are also computed by the ‘HFSS’. The characteristics of the proposed antenna, such as operating bands, bandwidths, far-field patterns, and antenna gains, are given in this thesis. It is believed that the proposed antenna structure with extremely low transmission losses is very suitable in millimeter and even in submillimeter systems.
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