Design and implementation of low sidelobe substrate integrated waveguide longitudinal slot array antennas

Low sidelobe longitudinal slot array antennas are investigated based on substrate integrated waveguide (SIW) technology. The design method consists of the characterisation of the radiating element, the synthesis of the linear array and the development of the planar array including a feeding power divider by performing fullwave electromagnetic simulations for the final accurate design. Two planar slot array antennas are fabricated with a normal printed circuit board (PCB) process. Low sidelobe features are verified by the measured results which are in agreement with the simulated results. For an 8 x 8 SIW slot array antenna, the measured sidelobe levels (SLLs) are below 236 dB in the H-plane and below 225 dB in the E-plane with the Gain of 20.3 dB at 9.9 GHz. And for a 16 x 16 antenna, the SLLs are below 230 dB both in the E-plane and H-plane with the Gain of 24.4 dB at 10 GHz. The achieved design goals on the radiation patterns therefore validate the proposed low sidelobe SIW slot array antennas to be valuable candidates for high performance communication and radar applications.