GB859945A - Improvements in or relating to waveguides - Google Patents

Abstract

859,945. Waveguides. ELECTRIC & MUSICAL INDUSTRIES Ltd. May 2, 1957 [May 12, 1956], No. 14855/56. Class 40(8). [Also in Group XL(c)] The wall of a waveguide comprises or includes a coil of insulated wire whereby a longitudinal or transverse magnetic field may be set up in the guide, the coil being wound close enough to prevent escape of high-frequency energy. As shown in Fig. 1, the waveguide wall consists of a coil 1 which provides a longitudinal H.F. alternating field within a ferrite element 14. The element may entirely fill the guide or may be supported by a polystyrene foam member 15. The coil 1 is flanked by further coils 4, 5 separated from the coil 1 by aluminium spacers 6, 7 having radial gaps to prevent the forming of a shortcircuited turn. The coils 4, 5 are insulated from the coil 1 and no current is passed through them. They are included to prevent the waveguides 8, 9 from presenting short-circuited turns to the coil 1. The coils 1, 4, 5 may be wound as one coil progressively from one end to the other, the coil being subsequently cut at the appropriate places. The waveguide may be round or square. A transverse field may be provided by a pair of oppositely-disposed spiral coils 15 arranged in apertures in the wall of a round or rectangular waveguide 14. Each coil may be surrounded by a further flat annular coil separated from the inner coil by a split ring.