Abstract: A dual band monopulse radar antenna has a planar configuration and is divided into four quadrants. The antenna includes a circular plate with an array of slots formed in each quadrant. The slots are configured for operation at a first frequency, such as X-band. Four respective slot waveguide feeds are provided, one for each array of slots in each quadrant. A dielectric layer, such as Teflon, is mounted on the surface of the plate. Each quadrant of the antenna is provided with an array of microwave patch elements comprising a plurality of rows of patch elements fed by a microstrip line. Each array of microwave patch elements is fed by a waveguide. The antenna has eight waveguide couplers, two for each quadrant of the antenna with one waveguide feed in each quadrant for the slot array and one waveguide coupler in each array for the microwave patch element array.