Quasi-Optical Excitation of a Modulated Dual-Polarized Leaky-Wave Antenna

A multi-beam dual-polarized antenna fed by four quasi-optical beamformers is presented in multi-layer substrate integrated waveguide (SIW) technology. The quasi-optical beam-forming networks are folded in two layers exploiting a pillbox transition based on several coupling slots and a SIW parabolic reflector. Such beamformers allow to transfer efficiently and over a large band the energy coming from feeding sources in the lower substrate to the radiating part located in the uppermost layer. The radiating part consists of a two-dimensional periodic array of cross-slots etched in the upper conducting plane. The slots are tapered in size to achieve high aperture efficiency and a side lobe level (SLL) below -25 dB. The proposed antenna system operates in the entire 28 GHz 5G band. The footprint of the antenna is equal to the radiating aperture with a size of 11.6 × 11.6 cm
²
. The proposed structure features 360° scanning in the azimuth plane by beam switching and more than ±55° in the elevation plane by frequency steering with a realized gain higher than 20 dBi.