Abstract: 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 TE.sub.10 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.

Abstract: Eight radiators, disposed along a line, are coupled to a radar via a Butler matrix. In response to a transmitted signal from the radar, inverse transform signals that have amplitudes representative of values of a sinusoid in an angular range of zero radians to .pi. radians is applied to the Butler matrix. The inverse transform signals cause excitation to be applied to two of the radiators that are adjacent to each other. The inverse transform of the sinusoid at the output of the Butler matrix, in addition to allowing the excitation of two adjacent pairs of radiators, also provides a transmitted beam having reduced beamwidth and lower sidelobes. The two adjacent radiators are selected by selecting a phase pattern of the inverse transform signals.