Antennas for high cross-polarization discrimination and security

摘要

Methods and systems for detection of threats in secure areas are disclosed. Microwaves are transmitted into high traffic areas and are reflected off or transmitted through targets within that area. The resulting signals are detected at receiving antennas which are designed to have a high cross-polarization discrimination (XPD) such that co- and cross-polarizations of the resulting signals are separable for further processing. The receiving antennas of the present invention comprise elliptical antennas with a double-ridged waveguide on the interior and a conically-shaped exterior. This particular design for the receiving antennas allows to technologically obtain an XPD of about 30 dB or more for solid angles measured from a receiving antenna's boresight (the main lobe axis), and formed by rotating the corresponding 30-degree planar angle around the main lobe axis, the solid angles measuring approximately 0.84 sr, in a frequency range between 9.5 and 20 GHz.