Multimode feed for a monopulse radar

摘要

A rectangular waveguide housing and a waveguide radiator have coaxial cavities that are contiguous. A pair of perpendicular walls intersect substantially on the axis of the housing to form therein four similar rectangular subwaveguides that may be excited to propagate electromagnetic waves in a TE10 mode. The walls have edges that are in the boundary between the contiguous cavities. A pair of intersecting tabs extend from the edges into the radiator. Additionally, a protrusion extends within the radiator from the intersection of the tabs. The polarities of the waves in the subwaveguides are selected to cause an electromagnetic wave to propagate through the radiator in either of two orthogonal difference modes or a sum mode that has desired beam shaping properties. The protrusion causes one of the difference modes to have a desired polarization.