Loss reduction by air-region insertion to rectangular waveguide-fed oversized post-wall waveguide slot array antenna in the millimeter-wave band

In this paper, loss estimation in each part of the rectangular waveguide fed oversized post-wall waveguide-slot array antenna with the air layer is presented. The air-layer insertion reduces the transmission loss to enhance the antenna gain. We have reduced the dielectric loss in the radiating part from 3.5 dB for the fully-filled antenna to 0.5 dB for the partially-filled antenna. Similarly to insert the air-layer in the feed waveguide, transmission loss of the feeding part can be reduced by about 1/6. A new T-junction model with circular patches for reflection canceling is introduced and deigned in the 60GHz band.