GB1299032A - Improvements relating to waveguides - Google Patents

Abstract

1299032 Waveguide twists H J RIBLET 19 May 1971 [17 July 1970] 15704/71 Heading H1W A waveguide twist comprises successive sections of rectangular waveguide arranged at an angle to each other and inclined walls which replace parts of the walls of the sections and eliminate the abrupt steps between sections. The normal rectangular section is modified by replacing the planar narrow walls with circular arcuate walls centred upon the axis of the section. The modified sections have the same area as the waveguides which it is intended to join by the twist. Part of the twist is shown in Fig. 5, where 1A, 2A are half-lengths of adjacent sections. The sections are preferably onequarter wavelength (#g/4) long, so that the axial distance between planes EFGH and ABCD is equal to #g/4. A suitable inclined wall for eliminating the step LMK is shown in chain line at AEM where the points A, E lie at corresponding corners of the successive half-sections 1A, 2A and the point M lies at the intersection of the broad walls of the half-sections. The line AE lies on an imaginary circular cylinder 10 and the portion JE lies on the narrow wall HEKD of half-section 2A. The other steps are eliminated in a similar manner and Fig. 6H shows the result. Each half-section presents an inductive reactance to the propagated wave and this inductance may be tuned out by enlarging the broad dimension of the twist in the vicinity of each transition. The resultant enlargements 6, 7 form portions of an imaginary annulus 8. Alternatively, the tuning may be provided by screws in the broad walls. The inclined walls may have an area more restricted than shown. Thus, the point M may be chosen to lie somewhere between the corner L and the mid-point of the broad side of the section.