| Two subjects are discussed in this Thesis, Dual-band High-Gain CircularlyPolarized Antenna for Inmarsat Communications, UWB Band-Notched MonopoleAntenna with SRR structure.As for the study on Dual-band High-Gain Circularly Polarized Antenna forInmarsat Communications, four works are reported. First, based on the Circularpolarized antenna theory, two pair of crossed bowtie antennas are adopted to get wideimpendence bandwidth which receiving band is1525-1558MHz and transmission bandis1626.5-1660.5MHz. Second, a bowl-shaped reflector is designed to achieve highgain. Third, Wilkinson power divider with equal magnitude and90°phase differenceand adjustable integrated balun are adopted to get wide axial ratio bandwidth (ARBW)and the Circularly Polarized (CP) radiation. Finally, experiments are accomplished bythe antenna. Measured results of the fabricated antenna prototype verify simulationswith reasonably good agreements. The new antenna’s impedance bandwidth coveringthe band of inmarsat communication system from1525MHz to1660.5MHz, while thegain is greater than9dB, AR is less than3dB and the Half-power beamwidth (HPBW)is45°. Compared with other reported inmarsat antennas, the proposed antennapossesses much higher gain, larger CP bandwidth and is more suitable for high latitudeInmarsat Satellite Communication systems. The antenna has been used a lot.As for the study on UWB Band-Notched Monopole Antenna with Split RingResonator (SRR) structure, four works are reported. First, based on ultrawideband(UWB) antenna theory, the new antenna is designed. The antenna’s impedancebandwidth covering the bands of3.1–10.6GHz. Second, by adding SRR on the centerof the radiating patch, notched band in3.3–3.7GHz for the WiMAX system is achieved.Third, the SRRs are adopted next to the microstrip feeding. The antenna exhibit goodbandstop characteristics to reject the WLAN bands (5.15–5.825GHz bands) anddownlink of X-band satellite communication systems (7.25–7.75GHz bands). Finally,experiments are accomplished by the antenna. The VSWR and radiation patterns of thefabricated antenna are presented, which prove that the designed antenna is a good candidate for various UWB applications. |
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