The analysis and design of dual-polarization square-waveguide phased arrays

Square-waveguide elements capable of radiating and receiving any of four different sets of dual polarizations were considered. Each element may consist of as many as 8 matching sections of square waveguide in tandem. The known solution to a "standard" phased-array problem was used to synthesize the solution for the many-junction element, and a computer program was developed to implement the solution. A systematic investigation of the performance characteristics of large dual-polarization phased arrays of square waveguides was carried out. Coupling between radiated polarizations and active reflection coefficient were computed for two wide-bandwidth (20 and 25 percent of center frequency) designs for dual-linear, dual-circular, and dual-scanned polarization states. A simple design procedure that yields well-matched practical elements with high polarization isolation was developed. Various phenomena peculiar to dual-polarization excitation were identified and are discussed. The theoretical predictions are supported by experimental evidence obtained by means of two infinite-array simulators and a 267-element array.