System and Method for Interrogating and Locating a Transponder Relative to a Zone-of-Interest: 7,573,369

A directional warning system and a method of warning of friendly forces. In one embodiment, the system includes: (1) a conductive shield having an opening at an end thereof and a radio frequency absorptive material located on an inner surface thereof, (2) a Luneberg lens located within the conductive shield and (3) a plurality of feed horns located proximate a portion of the Luneberg lens that is distal from the opening and arranged relative thereto based on a zone-of-interest with which the directional warning system may be associated.