| UWB (ultra-wideband) antennas have been widely used in the fields ofelectromagnetic monitoring, EMC measurement, UWB radars, etc. as the front ends ofUWB systems. As one kind of UWB antennas, horn antennas are widely used due towide impedance bandwidth, great directional radiation, high gain and high powercapacity. The horn antenna proposed in this dissertation features simple configuration,easy fabrication and great directivity. Compared to narrowband antennas, UWBantennas could achieve wide bandwidth, stable performances over its bandwidth, lowpower loss, large information capability, strong anti-interference and penetrating ability.Dual-polarized antennas have been used widely in these years. Duplex modescould be realized in the field of communication, leading to smaller number of basestation antennas. In the field of measurement, it’s unnecessary to change the polarizationof the antenna, so the working efficiency can be improved greatly. For the developmentof future wireless communication, antenna miniaturization, radiation characteristics,radiation gain stability and wideband impedance bandwidth should be paid attention tosimultaneously.Firstly, based on Vivaldi antenna structures and corresponding antenna basic theory,analysis concerning antenna characteristic impedance, cutoff frequency and radiationcharacteristics is carried out and design of single polarized antenna is achieved. Basedon this antenna, dual-polarized antenna is proposed which could work in the frequencyrange of3.1~10.6GHz. The radiation characteristics are improved efficiently by loadingcorrugations and chokes.Secondly, based on the theory concerning circular ridged waveguide, dominantcutoff wavelength, characteristic impedance, etc. of ridged waveguides are analyzed andcalculated, leading to the design of an open-boundary dual-polarized horn antenna. Byloading rectangular metal structure, funnel-shaped metal structure and optimizing thedistance between the feeding probe and the end of the ridge, a dual-polarized hornantenna is designed finally which exhibits excellent working characteristics in thefrequency range of2-18GHz.Thirdly, commercial EM simulation software CST is used to carry out simulationin this paper. Prototypes of two optimized antennas configuration are fabricated andmeasured. The measured results coincide with the simulation well. |
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