Two-layer slotted-waveguide antenna array with broad reflection/gain bandwidth at millimetre-wave frequencies

A 24×24 slotted-waveguide array antenna is presented in the paper. The subarray concept is introduced to provide a broad reflection and gain bandwidth. A waveguide feed network is proposed to feed equal amplitudes and equal phases to the subarrays; it is composed of two layers, and is thus more compact and simpler than conventional feed networks. The subarray is made up of the feeding waveguide coupling slot, radiating waveguide and radiating slot. The measured reflection bandwidth is 5.5% (VSWR ≤2.0) and 9.5% (VSWR ≤2.7). The antenna gain varies within 2.1 dB over 4 GHz (9.5%). The maximum gain is 33.8 dBi at 41.5 and 42.5 GHz.