| Summary: | 碩士 === 逢甲大學 === 通訊工程所 === 97 === A novel electromagnetic band-gap structure is proposed in this study. The proposed EBG structure is designed and developed to provide two stop bands at 2.8GHz - 3.2GHz and 4.3GHz - 4.8 GHz on a standard FR4 substrate. By properly designing the unit cell dimension and arranging its location, the pronounced surface waves can be suppressed. Also, the mutual coupling can be reduced when the EBG are applied to electromagnetic compatibility.
Besides, we used the proposed EBG structure to design superstrates. A 2×2 EBG array and a 4×4 EBG array had been separately fabricated to compose the superstrates. The EBG superstrates were combined with a patch antenna and a monopole antenna, respectively. The distance between antenna and superstrate is one half of wavelength at antenna’s operating frequency. Moreover, the effects on antenna gain and directivity under one and two layers of superstrate were investigated. The experimental results show that the antenna gain is improved obviously when the superstrate are with two-layer EBG structures. The antenna gain has a 2.5dB ~ 4dB increase at operating frequency. The gain performance has a remarkable promotion.
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