Model antenna of 76 GHz post-wall waveguide fed parallel plate slot arrays

We have designed and fabricated a 76 GHz post-wall waveguide fed parallel plate slot array. We have realized uniform field distribution over most of the aperture with 4 dB amplitude and 20-degree phase ripples. The model antenna has achieved 29.7 dBi gain with 45% efficiency at 76.75 GHz even though it has a large reflection of -6.33 dB (23.2 %) at the input aperture. This result indicates that this antenna itself has a potential of high efficiency of about 55% after improvement of the input aperture by reduction of the reflection.