GB814346A - Improvements in or relating to wave guide systems - Google Patents

Abstract

814,346. Non-reciprocal waveguide devices. LIGNES TELEGRAPHIQUES ET TELEPHONIQUES. March 6, 1957 [March 15, 1956], No. 7508/57. Class 40 (8). A non-reciprocal attenuator comprises a section 8 of rectangular waveguide along which a TE no (where n > 1) wave may be transmitted and a number of ferrite elements 10, 11, 12 arranged in the section, the elements being subject to transverse magnetic fields. The elements are in the form of thin rectangular plates and are situated at points where the longitudinal and transverse magnetic components of the wave are equal, e.g. at points where the magnetic field of the wave is circularly polarized. For a TE 20 wave there are four such positions along the direction of the broad dimension of the guide and elements 10, 11, 12 are situated at three of these. Since the sense of rotation of the circularly polarized field at the position of plate 12 is opposite to that at the other two positions, it is necessary to provide two oppositely directed transverse magnetic fields in such a manner that the sense of rotation is positive (anticlockwise when seen in the direction of the field) for all three plates. Under such circumstances, the wave is absorbed in the ferrite elements. If the direction of propagation is reversed, the sense of polarization is changed from positive to negative and no absorption of energy takes place. The magnetic fields are produced by two U-shaped magnets (not shown), one for the plates 10, 11 and one for the plate 12. The guide section is connected at either end by mode-converters 6, 7 to waveguides 5, 4 which have half the width of the section 8 and support a TE 10 mode wave. The converters 6, 7 are in the form of H-bends, the corners of which are cut off by walls 17 of length a#2, where a is the wide dimension of the guides 5, 4. The walls 17 make an angle of 45 degrees with the axes of the guides.