Scanning barrier for the discrimination and counting of objects and more specifically of vehicles in transit through a laminar barrage of electromagnetic microwaves

Claim 1

A scanning barrier for detecting objects in a scanned area, comprising a transmitter for transmitting across the scanned area a laminar barrage of electromagnetic microwaves having a thin width and a defined height, and a receiver for receiving said transmitted microwaves crossing the scanned area, said transmitter comprising an illuminator comprised of an oscillator for producing a wave beam operating at the millimeter wavelength range and a slit wave guide coupled to said oscillator, said slit wave guide having slits in a fan-like arrangement, whereby each of the slits emits a constant portion of the generated power of the wave beam to obtain an even wave front having a constant phase, said receiver being formed of a plurality of separate and individual vertically adjacent elemental receivers, each elemental receiver receiving a horizontal slice of the laminar barrage, each of said elemental receivers comprising a low gain horn antenna for receiving the horizontal slice of the laminar barrage, a crystal video receiver respectively coupled to each of said horn antennas and circuit means respectively coupled to each output of a respective crystal video receiver whereby each of said elemental receivers produces a direct voltage output corresponding to the interruption of the laminar barrage to that elemental receiver by an object in the area, and wherein the sensitivity of the barrier is dependent upon the aperture angle of each of said horn antennas.