A 64-element array antenna for 58 GHz

A planar array of box horns is presented for the frequency band 57.2-58.2 GHz. The horns are fed in parallel with a waveguide feed network. Improved T-junctions are used to connect the waveguides. The horns are divided into two subarrays shifted sideways in order to reduce the grating lobe in the H-plane, which is due to the large element spacing. The radiation pattern of the horn is also optimized to reduce H-plane sidelobe levels. The measured H-plane sidelobe level is below -35 dB at angles larger than 18/spl deg/ from boresight with a gain higher than 31 dBi. The measured return loss exceeds 17 dB over the band 57.2-58.2 GHz.