Waveguide for use in dual polarisation probe system

A method of receiving at least first and second orthogonally polarised signals in a frequency range in a single waveguide and providing at least two outputs in a common longitudinal plane for providing a flatter characteristic across the frequency range, said method comprising the steps of,

• providing a first probe in said waveguide to receive a first orthogonally polarised signal,
• providing a reflecting means in said waveguide parallel to and downstream from said first probe for reflecting said first orthogonally polarised signal and for allowing passage of said second orthogonally polarised signal,
• providing a second probe in said waveguide parallel to and downstream of said reflector means, said second probe being substantially orthogonal to said second orthogonally polarised signal which passes the second probe without being received by the second probe, providing a signal reflecting and rotating means at the end of the waveguide for reflecting a first component of said second orthogonal signal back towards said second probe,
• allowing a second component of said second orthogonal signal to travel towards said waveguide short circuit, modifying the length of said second component such that it has a different cut-off wavelength from said first component,
• reflecting said second component from said waveguide short circuit,
• recombining said first and second reflected components of said second orthogonal signal to create a recombined reflected signal, said recombined reflected signal being in the same plane as said second probe for detection thereby, said first and second reflected components having inverse frequency characteristics which combine to create a flatter frequency response across said frequency range.

A waveguide for use with a dual polarisation waveguide system for receiving at least two signals which are orthogonally polarised, said waveguide comprising a waveguide tube into which at least two orthogonally polarised signals are received for transmission therealong, said waveguide having;

• a first probe extending from a wall of the waveguide into the interior of the waveguide, said first probe being adapted to receive said orthogonal signal travelling in the same longitudinal plane thereof,
• reflector means extending from the wall of the waveguide, through reflector means located downstream of the first probe lying in the longitudinal plane for reflecting signals in said first orthogonal plane back to said first probe means and allowing said signal in said second orthogonal plane to pass along the waveguide, second probe means located downstream of said first reflector means and extending from wall of said waveguide into the interior of the waveguide and lying in said longitudinal plane, signal reflecting and rotating means, including a short circuit at the end of the waveguide, located downstream of said second probe means for receiving, rotating and reflecting said second orthogonally polarised signal back along said waveguide such that the rotated and reflected signal is received by said second probe means, said signal reflecting and rotating means also including, a differential phase shift means disposed between the second probe and the short circuit, said differential phase shift means having a slightly asymmetrical cross-section, whereby said first and second components of said second orthogonally polarised signal are phase shifted with respect to each other in the differential phase shift portion, then reflected respectively from said short circuit before being further phase shifted when travelling back through the differential phase shift portion for recombination, said first and second components having different cut-off wavelengths, to provide a recombined signal for detection by said second probe means.