System separating filter for separating first and second doubly polarized frequency bands

A system separating filter for separating first and second signals consisting of respective doubly polarized first and second frequency bands of different frequencies, said filter comprising:

• first, second and third doubly polarizable series connected waveguide sections, said first waveguide section having an inner cross section such that both of said first and second frequency bands can exist therein with their dual polarizations, said second waveguide sections serving as a transition between said first and third waveguide sections, and said third waveguide section having an inner cross section such that at least said second frequency band can exist therein with its dual polarizations;
• means for preventing the propagation of said first frequency band from said second waveguide section into said third waveguide section and for forming standing waves of said first frequency band in said second waveguide section;
• first and second coupling means, each including a pair of coupling elements symmetrically disposed opposite one another in the walls of said second waveguide section and each associated with a separate one of the two directions of polarization, for coupling out the respective polarizations of the signals in said second waveguide section and for passing said first frequency band and blocking said second frequency band with the electrically effective reflection plane of said coupling means for said second frequency band effecting total reflection of said second frequency band;
• a first hybrid circuit means, having its inputs connected to the outputs of said first coupling means, for providing an output signal corresponding to one polarization of said first frequency band at its summing output;
• a second hybrid circuit means, having its inputs connected to the outputs of said second coupling means, for providing an output signal corresponding to the other polarization of said first frequency band at its summing output;
• and a polarization filter connected to said third waveguide section for providing separate output signals corresponding to the respective polarizations of said second frequency band.