| Summary: | 碩士 === 國立臺北科技大學 === 電腦通訊與控制研究所 === 92 === In this thesis, the slot antennas designs on dual-band, wide-band and circularly polarized operation were studied. The design of the slot antenna is based on the square slot-ring antenna to achieve dual-band and broad-band. The dual-band operation is demonstrated by square metal-sheet of square slot-ring. Two rectangular metal-sheets produced another slot-ring with a new resonant frequency. The frequency ratio of the proposed dual-band square slot-ring antenna reaches 1.46-1.79. Two resonant frequencies are produced by same method, which mention above with square sheet-metal of square slot-ring antenna etch become three rectangular metal sheets. In order to reach broad-band operation the frequency ratio of two modes is reduced to about 1.31. The Results of experiment bandwidth achieves 952 MHz (44.91 %, @ 2120 MHz) and the radiation pattern of two operation frequencies is similar.
In this study, circularly polarized antenna is designed with using microstrip line fed by square ring-slot antenna. A new design with inverted L shaped microstrip metal sheet at right side of the square wide slot antenna was designed to produce another orthogonal mode. A 3/8 λg impedance transformer is applied for impedance matching. Experimental results show that 3 dB axial ratio bandwidth reaches 165 MHz (8.37 %, @ 1972.5 MHz). The designed circularly polarized antenna pattern shows a broadside pattern with available bandwidth and gain of 4 ± 0.4dBi.
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