Compact Center-Fed SIW Slot Array Antenna With Low Sidelobe Level

A compact single-layer substrate-integrated waveguide (SIW) slot array antenna with high aperture efficiency and low sidelobe level (SLL) is proposed in this work. The array antenna comprises four linear slot arrays in parallel. By feeding at the center using a novel serial SIW power divider, each linear array is converted into two shorter ones. In addition, to resolve the problem of aperture blockage, slots are etched on the top surface of the designed SIW power divider without damaging the divider. Consequently, high aperture efficiency and suppressed SLL in H-plane can be obtained. Meanwhile, the cross-polarization (X-pol) of the antenna is not compromised by these added slots, reason of which is elaborated. Moreover, the proposed antenna is realized on a single-layer substrate, thus slashing the fabrication complexity and cost, which is critical for mass production. Experiments show that the proposed antenna maintains low SLL in both E- and H-planes throughout the entire impedance bandwidth from 77.6 to 81.8 GHz (5.3%). At the center frequency, the gain is 19.1 dBi (53.4% aperture efficiency), and the SLL is −17.1 dB in H-plane and −16.8 dB in E-plane. Due to good overall characteristics, the proposed center-fed SIW slot array antenna is a good candidate for millimeter-wave (mmWave) applications.