Dual-Layer SIW Multibeam Pillbox Antenna With Reduced Sidelobe Level

In this letter, a dual-layer substrate integrated waveguide (SIW) multibeam pillbox antenna with reduced sidelobe level (SLL) is presented. To avoid the problem of aperture blocking, the feeding network and an antenna array are placed in different layers connected through an SIW parabolic quasi-optical system. Aiming to reduce the SLLs, two extra parabolic reflectors are introduced into the parabolic quasi-optical system placed on both sides of the central parabolic reflector. Moreover, by adding some metal posts in the antenna array section, a further reduction in SLLs can be achieved. The proposed antenna, operating at 28 GHz, has been verified by measurements, showing good performance over a coverage angle of ±45°, and the SLLs of all the beams are lower than -12 dB.