Modular hybrid architecture for a large aperture circularly polarized shaped-beam antenna

In this work the design, manufacturing procedure, and testing of a 6.4 meter long antenna for X-band airport surveillance radar applications is presented. This antenna operates with circular polarisation and produces a cosecant-squared shaped beam pattern in the elevation plane. To reduce manufacturing costs, the antenna has a modular architecture consisting of a number of identical microstrip subarray panels connected by a large waveguide beam forming network along the horizontal array axis. Each panel is structured as a two-dimensional subarray realized on a multilayered planar substrate. The subarray feeding network and radiating patches exploit a new technology recently investigated by the authors and exhaustively tested in many measurements fixtures as reported in previous publications. The assembled antenna provided with a sealed radome is mounted on a rigid structure that supports the antenna on a rotating platform as in real operating conditions. A complete set of measurements and tests providing a thorough characterisation of the realised antenna prototype is reported.