| Summary: | 碩士 === 中華科技大學 === 飛機系統工程研究所在職專班 === 104 === With the development of GPS integrating into aircraft navigation system technique, many researchers in aviation fields pay much attention to the GPS antenna which is capable of working at multi-frequency simultaneously. A dual-frequency circularly polarized microstrip antenna working at L1 band of the GPS 1575MHz and L2 band 1227 MHz is designed in this paper by using two corner-truncated square patches respectively fabricated on substrates with the same dielectric material fed by a single probe. Then the performances of the fabricated antennas were simulated by using software HFSS. At the same time, we measured and analyzed the physical GPS L1/L2 antenna equipped on a helicopter. The GPS antennas equipped on a helicopter were belonged to the broad-band antennas. However, the signal received by helicopter antenna might be more easier to be interfered by noise incurred from those unnecessary frequencies than the designed antenna if there is no sensitive filtering circuit on the back-end processing units. While the antennas simulated by software were narrow-band antennas, all its performances could satisfy the demands and applications of GPS system, furthermore, its fabrication processes are uncomplicated.
Keywords: microstrip antenna; GPS; dual-band ; circular polarization; HFSS
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