GB965244A - Improvements in or relating to wave-guide devices - Google Patents

Abstract

965,244. Waveguide switches. PHILIPS ELECTRICAL INDUSTRIES Ltd. Dec. 13, 1960 [Dec. 16, 1959], No. 42851/60. Heading H1W. The direction of polarization of a plane wave within circular waveguide 2 and hence its distribution between outputs 12, 14 is determined by the disposition of a twistable conductive strip S 1 . Assuming that the untwisted strip lies in the plane of the drawing, an input wave polarized at right-angles to this plane will propagate from the rectangular input guide 1 to the rectangular output guide 14 without change. The strip is fixed at one end 4, 5 to the sides of the guide 2 and at the other end 7, 9 to a rotatable ring C whereby a variable degree of twist may be imparted to it. The plane of polarization of the wave is rotated through an angle equal to the angle of twist. Rotated waves have components lying in the direction of a probe 10 and these components are transferred to the guide 12. By means of an additional conductive strip S 3 arranged in the plane of the drawing one quarter-wavelength from the probe, the part of waveguide 2 lying beyond the probe is arranged to present an infinite impedance to wave components lying in the plane of the probe. Both the strips S 1 , S 3 have transverse slits which prevent generation of unwanted modes. Components polarized at right-angles to the probe are transmitted to the guide 14. Wave energy reflected from mismatches in the guide 14 is polarized at right-angles to the plane of the drawing and can be resolved into components lying in a direction co-incident with the rotated edge of the strip S 1 and at right-angles to this direction. The former component is absorbed by a lossy strip S 2 forming an extension of the strip S 1 . In the absence of the strip S 2 this component would be reflected into the guide 12. The other component propagates back along the strip S 1 into the guide 1.