Alternating phase fed single-layer waveguide slot array with interchangeable slot plates for multi-frequency operation

Alternating phase fed single-layer waveguide slot arrays are high gain, high efficiency and very low cost antennas. They consist of two components, a slot plate and a base plate, manufactured by punching and die casting respectively. As the size of the array and the gain becomes high, the bandwidth of the overall antenna becomes narrower. In order to cover the 1.71 GHz range allocated for 26 GHz FWA in Japan with 31.5 dBi gain, 10 types of arrays, each with 180 MHz bandwidth must be prepared. This paper proposes the band switching arrays in which only the slot plate is switched for each channel while the base plate is common for all channels. The degradation of the arrays with the base plate designed at the offset frequency is compensated by the slot deign. A 1 GHz band is covered with a gain reduction of only 0.3 dB which should be compared with 5 dB if not using interchangeable slot plates.