| Summary: | 博士 === 元智大學 === 通訊工程學系 === 98 === Fractal antenna constructed with fractal geometries, it presents miniature, multiband and wideband characteristics, and array effects. A novel unequal radius multi-ring array equation is proposed in this thesis to analysis the fractal array characteristics for designing the desired fractal array antenna. In practice, the lotus-pod circular fractal array is analyzed by the equation and verified by simulation. It is found that the analysis and simulation results of array characteristics are agreed.
Based on Descartes circle theorem, the circular fractal geometry formed by four mutually tangent circles, a circular fractal antenna is designed. The iteration method with space-filling and self-similar for 2-D geometry is used to design the circular fractal pattern in a square base. The initial four circles consisted of three inner mutually tangent circles and one outer circular slot, and the slot applied with CPW-fed, the circular fractal antenna is presented. In practice, the half-wavelength and quarter-wavelength designs with synthesis and design map are proposed.
CPW-fed circular fractal antenna presents the multi-band and wide-band responses, and the array radiation patterns. The broadband and dual-band responses (47.4% and 13.5% bandwidth) below -10 dB return loss, and the available radiation gains (peak gain 3.58 dBi and 7.28 dBi) at 0.98 and 1.84 GHz GSM dual-bands are achieved with half-wavelength design. The second broadband and dual-band responses (75.9% and 16.1% bandwidth) and available radiation gains (peak gain 3.16 dBi and 6.62 dBi) at 2.38 and 5.35 GHz WLAN dual-bands are presented with quarter-wavelength design.
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