Apparatus for effecting rotation of the plane of polarisation of plane-polarised electromagnetic waves

Claim 1

AN ELECTROMAGNETIC WAVE SWITCHING SYSTEM COMPRISING A LENGTH OF WAVEGUIDE WHICH CONTAINS FERROMAGNETIC CERAMIC MATERIAL AND WHICH IS ARRANGED TO EFFECT ROTATION OF THE PLANE OF POLARIZATION OF PLANE-POLARIZED ELECTROMAGNETIC WAVES TRANSMITTED THERETHROUGH IN DEPENDENCE UPON THE MAGNETIC FIELD IN WHICH THE FERROMAGNETIC CERAMIC MATERIAL LIES, AN INPUT WAVEGUIDE CONNECTED TO ONE END OF SAID LENGTH OF WAVEGUIDE, FIRST AND SECOND OUTPUT WAVEGUIDES CONNECTED TO THE OTHER END OF SAID LENGTH OF WAVEGUIDE TO PASS TO THE FIRST OUTPUT WAVEGUIDE ELECTROMAGNETIC WAVES SUPPLIED BY SAID LENGTH OF WAVEGUIDE WITH A FIRST PREDETERMINED PLANE OF POLARIZATION AND TO PASS TO THE SECOND OUTPUT WAVEGUIDE ELECTROMAGNETIC WAVES SUPPLIED BY SAID LENGTH OF WAVEGUIDE WITH A SECOND PREDETERMINED PLANE OF POLARIZATION WHICH IS DIFFERENT FROM THE FIRST PLANE OF POLARIZATION, TWO POLARIZATION-SENSITIVE COUPLINGS WHICH ARE SPACED AROUND SAID LENGTH OF WAVEGUIDE AND EACH OF WHICH SUPPLIES AN ELECTRIC SIGNAL HAVING AN AMPLITUDE DEPENDENT UPON THE PLANE OF POLARIZATION OF WAVES TRANSMITTED BY SAID LENGTH OF WAVEGUIDE AFTER ROTATION THEREIN, MEANS TO PROVIDE A MAGNETIC FIELD IN WHICH SAID CERAMIC FERROMAGNETIC MATERIAL LIES, COMPARISON MEANS TO COMPARE THE ELECTRIC SIGNALS SUPPLIED BY THE TWO POLARIZATION-SENSITIVE COUPLINGS AND TO CONTROL THE LAST MENTIONED MEANS TO VARY THE MAGNETIC FIELD AS A RESULT OF SAID COMPARISON, AND SWITCHING MEANS SELECTIVELY HAVING FIRST AND SECOND CONDITIONS TO CONTROL THE COMPARISON MEANS SO THAT IN SAID FIRST AND SECOND CONDITIONS THE MAGNETIC FIELD IN WHICH THE CERAMIC FERROMAGNETIC MATERIAL LIES IN SUCH THAT ELECTROMAGNETIC WAVES SUPPLIED OVER THE INPUT WAVEGUIDE ARE PASSED MAINLY TO THE FIRST AND SECOND OUTPUT WAVEGUIDES RESPECTIVELY.