Dual-Polarization and Low-Sidelobe Corrugated Rectangular Horn Antennas for Outdoor RCS Measurement

Outdoor radar cross section (RCS) measurement suffers background clutter. Such clutter needs to be minimized, especially when measuring low RCS level objects. To do this, a pair of corrugated horn antennas with a rectangular aperture has been designed, fabricated, and measured to improve the performance of outdoor RCS measurement. This antenna consists of a coaxial-waveguide adaptor, a square-rectangular wave-guide transition, a corrugated rectangular horn, and chokes. A comparison of the performances of several corrugation profiles is provided. The tangential profile surpasses others because it provides the necessary low sidelobe level and narrow elevation beamwidth. The proposed antenna achieves -30 dB sidelobe level, fan-shaped beam pattern, and dual-polarization with -26 dB cross-polarization level over the band from 8.5 GHz to 12.5 GHz. The effectiveness of the antenna has been verified experimentally on a roof with two corner reflectors that were deployed intentionally to enlarge the effects of back-ground clutter.