Design Of A Satellite Antenna And A UWB Antenna With Band-notched Characteristic

The satellite antenna and band notched antenna are the two main works discussedin the thesis.Satellite communication is a communication between the base-station and terminal.With the satellite, a communication is realized with the advantage of long-distance,broad range of coverage, large-capacity, wide band transmission. So a L-band antennafor INMARSAT communication is designed at the request of a company. For meetingthe request of polarization, working band and gain, a crossed bow-tie(CBD) antennawith a Wilkinson power divider is adopted to realize circular polarization and a reflectoris used for improving the gain. Through commercial software CST MWS, an antennawith32%impedance bandwidth,7.3%axial ratio bandwidth, half-power beamwidth of90degrees, and minimum antenna gain of6dBi has been developed for INMARSATapplications. The CBD antenna possesses wider axial ratio beam-width compared to thereported antennas and is more suitable for the high latitude communication satelliteapplications.For UWB technical presents better performance then narrowband communicationin the term of power, positioning, UWB antenna for3.1-10.6GHz has attractedconsiderable interest in recent years. However, some several narrow bands, such asWLAN, PERLAN/2, WIMAX are among the UWB band, so an UWB antenna withband-notched characteristic which can suppress narrow-band interference is necessaryto reduce the interference of systems and make systems work better. Therefore, thesecond main work in this paper is a design of a UWB antenna with dual band-notchedcharacteristics. Based on spiral electromagnetic band-gap (EBG) structure, combiningwith microstrip transmission line method, an antenna with dual band-notchedcharacteristics is designed. The measurements show an antenna which presentsOmnidirectional and stable radiation pattern in H-plane and has an impedancebandwidth of2.8-11GHz with VSWR<2, except the bands of3.4–3.85and5.1–6.2GHz which covers WIMAX and WLAN, HIPERLAN/2is designed throughcommercial software CST MWS. By using the microstrip transmission line method, the design of band-notched characteristics is independent on the UWB antenna, whichincreases the flexibility in the design.