Compact primary source for W-band reflector antenna

A double slot array antenna pasted on the aperture of a standard WR-10 waveguide is presented. Its compactness and airtightness make it suitable for serving as a primary source for reflector antennas. Compared to a standard WR-10 open-ended waveguide, it acts as a small FSS to provide up to 12 dB return loss enhancement within 9% bandwidth centred on 94 GHz, whereas radiation pattern and gain are similar. Good agreement is found between measured and predicted characteristics between 90 and 100 GHz. A return loss improvement is of particular interest while considering an antenna system with short focal length.