Angularly Stable Linear-to-Circular Polarizing Reflectors for Multiple Beam Antennas

In this paper a new concept to improve the angular stability of linear-to-circular polarizing reflectors is presented. It is first explicitly demonstrated that existing design approaches heavily rely on the adjustment of the design stack-up, namely the substrate height and relative permittivity, to the desired operating frequency. An approach is then proposed for decoupling the performance from the substrate parameters. The proposed approach provides increased design flexibility, resulting in performance improvement. Insight on the operating principle is provided resorting to equivalent circuit models. Subsequently, the benefits of the angularly stable reflection polarizer are demonstrated by a practical example involving a multiple beam antenna implemented using materials and processes compatible with satellite missions. The antenna exploits an innovative quasi-optical beam former as primary feed combined with a cylindrical polarizing reflector. Numerical and experimental results from this antenna architecture are presented to confirm the improvements achieved with the proposed concept over existing designs. The close comparison of simulations with measurements that is achieved validates the concept and the design approach.