45/spl deg/ linearly polarised post-wall waveguide-fed parallel-plate slot arrays

A new configuration of three slots is proposed to radiate a 45/spl deg/ linearly polarised wave in post-wall waveguide-fed parallel plate slot arrays. The configuration consists of one radiating slot tilted to give the desired polarisation and two parallel /spl lambda//2-spaced reflection-cancelling slots without radiation in the boresight. A uniform aperture field is designed in a 76 GHz antenna. A good cross-polarisation level below -28 dB is achieved in the boresight. A gain of 29.8 dBi is obtained with 46.4% efficiency in a 5 cm square antenna.