| High-temperature superconducting (HTS) materials can significantly increase the efficiency of large microstrip patch antenna arrays by reducing the ohmic losses in the feed network. The efficiency of the individual microstrip patch antennas can also be significantly improved through the use of HTS materials. These efficiency increases are demonstrated through both theoretical and experimental investigations in this dissertation. Experimental results demonstrate an efficiency of approximately 89.9% for a K-band YBaCuO rectangular microstrip patch antenna compared to 85.2% for an identical copper rectangular microstrip patch. A circularly polarized four-element 20 GHz microstrip patch antenna array was also experimentally investigated and the gain for the YBaCuO array relative to the copper array at the same temperature was approximately 2.2 dB at 30 K and approximately 0.75 dB and 1.3 dB at 77K. The results demonstrate the benefits of HTS materials in microstrip patch antennas and arrays, however, the HTS materials and the high permittivity substrates, on which high quality HTS films are gown, provide interesting design challenges. Experimental results, which provide design information for microstrip patch antennas on high permittivity substrates, is provided and a model to predict the change in resonant frequency of a microstrip patch antenna as a function of temperature is also presented. |
