Advances in 94 GHz integrated horn monopulse antennas

Recent progress in integrated 94-GHz monopulse antennas is discussed. The structure consists of a single dipole suspended in one plane of an integrated horn cavity to obtain the sum pattern, and an antiparallel pair of dipoles suspended in a different plane of the same horn cavity to achieve the different pattern. Input impedances and coupling between the antennas were measured on a 1.2-GHz model using an HP8720B network analyzer. A monopulse antenna with a beam-lead commercially available diode was constructed with a design frequency of 92-GHz. The antenna was tested without the machined high-gain extension. The machined horn extension was then attached to the integrated horn antenna. The difference pattern measurements are shown. The null depth was measured at 92-GHz to be below -26 dB. Cross polarization remains well below -20 dB. The difference antenna generated similar patterns with sharp nulls below -23 dB from 84 GHz to 94 GHz, and appeared to be well matched to the diode throughout this range.<>