GB663820A - Coupling system for ultra high frequency transmission lines - Google Patents

Abstract

663,820. Impedance networks. BRITISH THOMSON-HOUSTON CO., Ltd., and KEITLEY, R. Sept. 22, 1948 [April 15, 1947], No. 10020/47. Class 40 (viii). [Also in Group XI] In an U.H.F. transmission system comprising a common length of feeding and fed lines along which these lines are mutually coupled for the transfer of energy between them, the coupling is effective over a distance which is a multiple of the wavelength and a gradual variation of the amount of energy transferred is ensured by a gradually varying dimension of the line sections which influences the degree of coupling. As shown, Fig. 8, the outer conductors of coupled coaxial lines 1, 2 are slit along the contiguous surface. The feeding line 1 tapers over several wavelengths, thus giving a reflectionless coupling. In a modification, Fig. 10 (not shown), the feeding line is not tapered, but the inner conductors of the lines are connected by a tapered vane. A wave-guide 1 feeding a coaxial line, Fig. 4, is tapered over several wavelengths, and probes 10 extend from the inner conductor 8 of the coaxial line into the waveguide through spaced apertures. The probes may be replaced by a vane, tapered at both ends and extending into the wave-guide through a slit. A wave-guide may be fed from a gradually tapered wave-guide through a slit, and two parallel wire lines may be coupled by reducing the spacing between the lines over several wavelengths. Dielectric material 19, Fig. 12, to be heated by ultra-high-frequency energy is tapered into a loop wave-guide 2, which is fed through a slit from a tapered waveguide 1. Any energy not absorbed by the load 19 continues to flow round the loop, which is so dimensioned that this energy reinforces the energy fed into the loop from guide 1. The dielectric material may form a seam between two pieces of wood, and the loop guide may be split at 18 to allow the load to be placed in position.