A planar high-gain antenna for millimeter wavelengths

The largest single component of a radio relay system is the antenna. Small antennas would promote the possibility of hiding the transmission system in the environment. In this paper a planar array antenna, in which box horns are used as radiating elements, is presented as a possible candidate for planar radio relay antennas at 40 GHz. The antenna consists of two parts, one containing the feed network and the other 256 radiating elements. The measured radiation pattern of a prototype antenna is very directive in both the E- and H-planes and a gain of 37 dBi at 39.2 GHz has been achieved. The highest sidelobes are at least 31 dB below the mainbeam in the H-plane and 16 dB in the E-plane.