GB1022365A - Improvements in or relating to wave-guide coupling - Google Patents

Abstract

1,022,365. Waveguide seals; travelling-wave tubes. SIEMENS & HALSKE A.G. Aug. 23, 1963 [Aug. 31, 1962], No. 33435/63. Headings H1D and H1W. A dielectric sealing member 6 having rotational symmetry is provided in a junction member 9, 10 extending between and perpendicularly to a pair of parallel rectangular waveguides 1, 3 the first of which is intended to be evacuated. The junction member contains three irises 7, 8, 11 which are designed to provide band-pass characteristics for E 01 mode energy in the member and to provide a characteristic impedance having a root equal to the product of the impedances of the guides 1, 3. In order to compensate for the presence of the dielectric seal 6, the central iris may have a larger diameter than the outer irises (Fig. 2, not shown). This compensation may also be effected by placing the seal 6 and its associated iris nearer to the iris 7 than to the iris 8. As shown in Fig. 3, the central iris 11 is made from a separate annular member which is held between two flanges 9, 10 which together form the junction member. A soldered seam 12 between flange 10 and annulus 11 is located within a closed annular chamber 13 formed between the flanges 9, 10. In a modification (Fig. 4, not shown), the central iris is formed from thin material and is provided with annular corrugations to absorb thermal stresses. It is sealed to the flange 10 by means of an 0-ring. In a further modification (Fig. 5), eccentric irises of reduced diameter are used, the junction member thereby comprising two coupled resonant cavities with the sealing member 6 extending across one of them. Where the waveguide 1 is extended for connection to a travelling- wave or transit-time tube 18, the axis of this tube is arranged at right-angles to the waveguide in order to prevent X-rays or electrons from hitting the window.