Search radar reflector antennas with extremely low sidelobes

Several different search radar reflector antennas have been developed for varying elevation coverage and frequency requirements. The trend has been towards extremely low azimuth sidelobes. This paper treats electrical and mechanical design of such antennas including results achieved using computer aided optimization procedures (CAD). The definition of reflector shape and contour and the associated electrical performance, are presented. Furthermore, theoretical analyses concerning reflector surface imperfections and frequency dependence are given. Mechanical analyses for minimizing mass and deformations at high wind velocities, by means of computer simulations, wind tunnel tests and careful material selection are also presented. The antennas are manufactured in a sandwich GFRP construction on precision moulds which have been milled using NC-machines. Input data tapes are generated directly from the theoretical design computations (CAM). These antennas have been tested at a computer controlled test range and sidelobe performance down to -60 dB has been demonstrated.