A chirped radio frequency signal is transmitted across an area of a potential threat. A reflected radio frequency return signal from an open barrel of a weapon at a location within the area of the potential threat is received at an incident angle through an aperture. An antenna at a position in an antenna array detects the reflected radio frequency return signal received at the incident angle through the aperture. The position of the antenna within the antenna array corresponds to a direction from which the reflected radio frequency return signal originates.