Design and experimental investigation of a wideband polarisation filter

The design of a wideband polarisation filter composed of a two-dimensional perforated flat conducting plate is presented. The experimental procedure used to verify the validity of the design algorithm is explained. The filter is used to suppress the cross-polarisation of both a horn antenna and a large array of dielectric resonators. Effective suppression of the cross-polarisation (in the order of 15 dB) was observed for both cases. The insertion loss is in the order of 2 dB in the case of the horn, and 0.6 dB in the case of the array antenna. The 10 dB return loss bandwidth is measured to be 15%. It is demonstrated that the filter can be installed in close proximity to the antenna radiating aperture without any significant degradation in its insertion loss or polarisation isolation performance.