Design of a 39 GHz band alternating-phase fed double-layer waveguide slot antenna with the underneath partially-corporate feeding circuit

The fabrication technique called “pressure bonding” by applying a pressing at ambient temperature which has very high mass-productivity is supposed to realize a 20×20 elements double-layer waveguide slot array. Since the electric contact can not be realized at all locations, an alternating-phase fed array is adopted in this study. A partially-corporate feeding circuit installed in the bottom layer below the radiating waveguides is introduced to decompose the whole antenna into 2×2 sub-arrays, and so as to achieve relatively wideband characteristics. The five-element sub-arrays in both feeding and radiating parts as well as T-junctions and input aperture are designed at 38.75 GHz. As the design results, a directivity of 33.7 dBi and the corresponding aperture efficiency of 70.0% are realized at the design frequency.