Radio signal polarization switching arrangement

Claim 1

A polarisation switching arrangement responsive to polarised radio signals ad capable of selecting signals having either one of predetermined states of linear polarisation, comprising a dielectric support block supporting a ferrite rod on a longitudinal axis of the block, a metal or metallised layer disposed on an external surface of the block around the ferrite rod, in axial alignment therewith, and an electrical coil wound around said layer, also in axial alignment with the ferrite rod wherein the metal or metallised layer constitutes a waveguide for said polarised radio signals, said electrical coil is selectively energisable to generate a magnetic field in one axial direction along the ferrite rod, whereby to select one said predetermined state of linear polarisation or in the opposite axial direction along the ferrite rod, whereby to select the other of said predetermined states of linear polarisation, orthogonal to said one predetermined state of linear polarisation, and opposite axial ends of the support block are so shaped as to compensate for the loading effect of the ferrite rod, and the dielectric support block has a circumferential recess bounded by a respective wall at each end of the block, said metal or metallised layer is disposed on a surface of the recess, and the electrical coil, wound around the layer, is contained within the recess.