Abstract: A dual beam monopulse antenna system includes a flat plate antenna (10). The antenna (10) comprises a plurality of slotted waveguides (20) which transmit radiation through slots (28). The antenna is divided into quadrants (12, 14, 16, 18) for monopulse operation. Each of the quadrants is provided with primary and secondary feed lines which are connected through directional couplers (42-136) to connecting lines (146-192) to the slotted waveguides (20). The primary feed lines (26, 28, 30, 32) are connected to a primary monopulse comparator network and the secondary feed lines (34, 36, 38, 40) are connected to a secondary monopulse comparator network. The summation terminals of the monopulse comparator networks are connected to a switch network (322). The azimuth differential terminals of the monopulse comparator networks are connected to a switch network (332). The elevation differential terminals of the monopulse comparator networks are connected to a switch network (342).