W-Band Low-Sidelobe Series-Fed Slot Array Antenna Based on Groove Gap Waveguide

In this letter, a low-sidelobe, high-efficiency, series-fed 2 × 24 slot array antenna at 93 GHz is proposed. The antenna can be divided into three separated layers and there is no need of electric contact between layers according to gap waveguide (GW) theory. To control the magnitude of the coupling energy and achieve −30 dB sidelobe quasi-Taylor weighing in radiation slots, transverse coupling slots in the middle layer are placed in a certain distance relative to the bottom gap waveguide center. Measure results agree well with simulation result, which demonstrates that the reflection coefficient of the antenna is lower than −10 dB from 91.6 to 94.4 GHz, with over 23 dB gain in the operating band. The 3 dB beamwidth of the E-plane pattern is lower than 4°, while the sidelobe level is lower than −20 dB. The whole antenna's efficiency is higher than 85%.