| Summary: | 碩士 === 國立彰化師範大學 === 電機工程學系 === 106 === In this thesis, two designs based on a compact slot array with two elements is proposed. For the first design, the array is designed with pattern reconfigurable capacity, and it is composed of two face-to-face slotted-patch antenna elements connected together through a slot line. By controlling the reverse voltages of dual varactors mounted on the slot line, the array can offer one omnidirectional pattern and two reverse unidirectional patterns in the H-plane. Moreover, each unidirectional pattern has a high front-to-back ratio. A prototype designed for 2.4 GHz WLAN applications is constructed. The experimental results show that the array has good impedance matching within the WLAN band as the radiation pattern is switched; besides, the peak gains are 6.5 dBi and 2 dBi for the unidirectional and omnidirectional radiation modes, respectively. As for the other design, the array is composed of dual circularly-polarized slot antenna elements also arranged in a face-to-face configuration, and they are simultaneously excited through a slot line. By properly controlling the excitation amplitudes and phases of the two radiating elements, the cross polarization and back radiation of the array can be effectively reduced. From the measured results, the proposed array can give an axial ratio of lower than 1 dB, a front-to-back ratio of higher than 12 dB, and a return loss of less than 10 dB in the frequency band from 2.04 to 2.4 GHz. For the two designs mentioned above, simulation results obtained with HFSS also agree well with the experimental data.
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