Design techniques for compact monopulse antenna feeds for W-band radar systems

Radical differences between system requirements require great flexibility in the design process for the millimeter-wave monopulse feed. A discussion is presented of the design approaches used for three monopulse feed systems: a three-channel multimode feed; a six-channel dual linear polarized feed; and a four-channel dual circular polarized feed. Each of these feeds was designed for a 94-GHz radar application. Performance levels achieved for each of these feeds include >35-dB null depth, >30-dB cross polarization, sidelobe levels >25-dB down, comparator insertion loss of <1 dB, axial ratios of 2 dB, pattern symmetry to BW/15 of >