A new reflector antenna design providing two different patterns

Antennas with cosecant squared pattern are designed for air-surveillance radar systems. These permit an adapted distribution of the radiation in the beam and causing a more ideal space scanning. In the practice a cosecant squared pattern can be achieved by a deformation of a parabolic reflector. Moreover, it can be achieved by using multiple feed antennas with normal parabolic reflector surfaces. A fan beam antenna which is a directional antenna producing a main beam having a narrow beamwidth in one dimension and a wider beamwidth in the other dimension can also be used for similar purposes. This pattern can be achieved by a truncated parabolic reflector or a circular parabolic reflector. Frequency selective surfaces (FSSs) have been used in the reflector antenna designs in recent years. A FSS is an array of periodically arranged patches or apertures, showing a particular filtering behavior. Its selectivity in frequency is obtained by the design and allows the transmission of signals in a certain frequency range only. This work is proposed to design a reflector antenna that provides both fan beam and cosecant squared pattern by using a FSS. For the simulation and optimization of the antenna, high frequency simulation software (HFSS) and SUPERNEC antenna simulation programs are used.