A low sidelobe multibeam slot array antenna fed by rotman lens

Abstract

A new type of compact multibeam longitudinal slot array antenna fed by Rotman lens in composite construction of microstrip and substrate integrated waveguide (SIW) technology is proposed for mobile satellite communications. The antenna is constructed in the form of two layers, which is a highly integrated approach to reducing the size. A novel parallel-coupled SIW slot coupler is designed to connect the Rotman lens and the slot array, also control the coupled power to follow a tapered distribution to achieve a low sidelobe for all beams. The antenna operates at 10.0 GHz and the Rotman Lens, as the beamforming network, can generate 7 beams over an angular sector of ±35° with 3-dB beamwidth in the azimuthal plane. The simulated results show that sidelobe level is lower than -21 dB for the central beam and better than -16 dB for the edge beams.