Design of broadband planar array composed of 2×2 slotted cavities fed by E-plane waveguide parallel-feeding circuit in millimeter-wave band

An 8×8 element array antenna is composed of the E-plane waveguide parallel-feeding circuit in the lower layer and the 2×2 slotted cavities in the upper layer. The E-plane waveguide parallel-feeding circuit consists of two plates and assembled at the center of the broad wall of the waveguide to achieve low-loss property and wide bandwidth simultaneously. The 2×2 slotted cavities are designed to obtain lower Q factor and an ideal radiation patter in combination with the array factor of the cavity arrangement. The simulated bandwidth with reflection lower than -15 dB were wider than 5 GHz. The sidelobe level was lower than -12 dB and the gain was 26.0 dBi at 73.5 GHz.