Radiation Pattern Simulation And Analysis Of Offset Reflector Antennas With Local Protuberant Distortion

An offset reflector with local protuberant distortion is modeled for the case that reflector surface is impacted possibly. The physical optics (PO) method based on the surface current integration is determined as the research method in the paper after comparison of some analytical methods. The radiation patterns of the feed are ascertained, and offset reflector antenna without distortion is modeled using the mode expansion method and calculated. The calculated results of the reflector antenna without distortion and the ones in the literature are matched well. The efficiency of program is validated. The size, height and form of the local protuberant distortion are described using distorted area, distorted amplitude and distorted taper, respectively. The antenna model, which is a kind of local protuberant distorted offset reflector antenna, is established and described making use of elliptical section generated by quadric intersection. The distortion reflector antenna is analyzed and its radiation patterns are obtained using the method of PO, and its analytic formulae are deduced. After simulating a kind of offset reflector with large focus to diameter ratio, the influence of the distortion on the radiation patterns is discussed as the distorted area, distorted position and distorted amplitude are changed, respectively. Six typical positions are selected in the reflector surface, appropriate rate of the distorted area and distorted amplitude are set, radiation patterns in the two major planes are calculated. Compared to the reflector antenna without distortion, some radiation characteristics, such as side-lobe level, half power beam width and cross-polarization level, are discussed.