Search

Based on practical antennas for indoor or outdoor communication and radar systems, a meander line polarizer is designed working as a radome a circular polarizer at the same time. It has simple design method, low cost, stable structure and good performance. The polarizer works with a linearly polarized horn antenna, and is placed at the open aperture of the horn. Therefore, the plate polarizer isolate and protect the antenna from external influence, which makes an extra high-cost radome unnecessary. Moreover, no complicated design is required to achieve circular polarization by the antenna itself. Simulation results show that this design provides wide axial ratio bandwidth more that 30% at 4 GHz. No noticeable gain degradation is observed, while pure circular polarization with axial ratio lower than 1 dB can be obtained at boresight in C band.

A part of constructed large-scale waveguide slot array antenna ultilized in Surface Monitor Radar(SMR) is proposed in this thesis, to which slotted rectangular waveguide with parallel metallic plates in this narrow-beam antenna is applied in order to restrain cross-polarization and obtain relative pure linear polarization so that excellent radiation performance is guaranteed. However, it is figured that the size of the parallel metallic plates can affect cross-polarization at centain frequency range we concern visibly, especially in such a large-scale array antenna, and vast slots graved in waveguide produce acceptable linear polarization but lead to severe cross polarization. Some tips to control cross polarization will be raised and datas about simulation and actual measurement will be shown in this article.