Method and apparatus of generating sum or difference signals corresponding to an apparent beam in a monopulse radar system

The invention relates to an apparatus and method for generating target range, azimuth angle, or elevation angle output signals corresponding to an apparent beam in a multiple-feed monopulse radar system. The multiple-feed monopulse radar system according to the present invention includes a transmitter/receiver unit, an adder/subtracter unit and a video comparator/adder unit. The transmitter/receiver unit is used to generate first and second actual antenna beams. Echoes caused by such actual beams are received and processed to provide first sum and first difference signals and second sum and second difference signals corresponding to the first and second actual beams, respectively. These signals are then supplied to the adder/subtracter unit which adds the first sum and first difference signals to provide a result SIGMA 1+K DELTA 1, subtracts the first sum and first difference signals to provide a result SIGMA 1-K DELTA , adds the second sum and second difference signals to provide a result SIGMA 2+K DELTA 1, and subtracts the second sum and second difference signals to provide a result SIGMA 2-K DELTA 2. These results are supplied to the video comparator/adder unit which generates the sum or difference signals corresponding to the apparent beam. Through the mere addition of a comparator/adder unit to a prior art multiple-feed monopulse radar system, the precision of target range, azimuth angle or elevation angle measurements may be increased dramatically without significantly increasing the size, cost or complexity of the monopulse radar system.