Dual-mode waveguides for variably polarised slotted waveguide array antennas

The polarisation selection mechanism in dual-mode slotted waveguide arrays requires that the exciting modes of the waveguide exhibit essentially identical phase and group velocities. This generally implies using an even and an odd mode of the structure, in an arrangement which provides useable current distributions in the slotted wall. This paper describes the results of a study of some waveguide configurations aimed at meeting these requirements in an array which was additionally intended to be frequency scanned.