Patent GB-612405-A (GB)
Title: Improvements in or relating to apparatus for controlling the passage of high frequency energy across a joint between two conductors
IPC: H01P1/06
Filed: 1943-06-10
Abstract: 612,405. Wave-guides; impedance transformers. SPERRY GYROSCOPE CO., Inc. June 10, 1943, Nos. 9381, 9382 and 9383. Convention dates, May 27, 1942, June 18, 1942, and June 29, 1942. [Class 40 (viii)] [Also in Group XL (c)] The escape of high-frequency energy at a gap or joint between two conductors, e.g. two relatively rotatable wave-guides, is prevented, and the flow of energy across the gap is facilitated; by wave traps in the form of two or more resonant concentric lines connected in cascade and having different characteristic impedances. As shown in Fig. 2, the guide 2 communicates with a relatively-rotatable guide 4 across a gap 3. One of the guides 2, 4 is provided with a half-wave extension 12<1> of larger diameter carrying flanges 11, 13<1>, the flange 13<1> being bent back for a quarter-wave length 21 lying close to the guide 4. The enlarged portion 121 may be increased in its axial length, and a series of inwardly projecting flanges 131, 21 provided (Fig. 3, not shown); or the flanges may be formed on the inner member 4 instead of the outer member 12 of the joint (Fig. 4, not shown). In Fig. 5, solid rings 33, 33<1>, 33<11> a quarter-wave long and separated by a quarterwave are secured to the wave-guide 2 and are enclosed by a flange 28 on the guide 4, as in Specification 612,404. Fig. 6 shows the application of the leakage-prevention system to a joint between wave-guides 102, 142 which are relatively rotatable about an axis 104 forming an energy transfer means between the guides as described in Specification 579,764.. The middle portion of the rod 104 is enclosed by a sleeve 105 which is secured to the guide 102, and the upper portion of the rod 104 is enclosed by a member 106 which is secured to the guide 142 and has an extension 115 surrounding the sleeve 105 and carrying an internal bush 140<1>. A ball bearing is provided between the bush 1401 and the sleeve 105. The bush 1401 is reduced in diameter at its outer end to form a quarter-wave gap 116<1> which communicates with a further quarter-wave gap 116 formed between the end of the bush 1401 and the clearance opening 114. This prevents escape of energy at the opening 114 and ensures low impedance for energy passing between the sections 105, 106. A similar arrangement prevents escape at the opening 129 between the sections 105, 107. Fig. 7 shows the system applied to an impedance-matching device for connecting two coaxial lines 212; 214; 213, 219, described in Specification 612,407. The two lines are connected by a short length of coaxial line comprising an inner member 222 with tapering ends 224, 225 and a slidable outer member 223 carrying a tunable stub line 243. The outers 212, 213 are tapered into the outer 223 by shaped blocks 226, 227 which do not quite reach the outer 223, and the gaps thus formed are a quarter-wave long. Behind these gaps are formed further quarter-wave lines comprising the slidable outer member 223, the reduced end portions of the outers 212, 213 and short-circuiting discs 231, 232 provided with spring fingers 234 for making good contact at points of low current intensity. In this way the impedance of the gaps at the inner ends of the blocks 226, 227 is made very small to currents flowing along the coaxial lines. The stub line 243 comprises a central rod 242 provided with a head 245 which slides in a slot in the member 222 when the stub line and the shell 223 on which it is carried are adjusted laterally. The stub line also comprises a cylinder 241 within which a tuning piston 256 is slidably mounted, thin layers of insulation being placed between the piston, the rod 242, and the cylinder 241. The piston is connected by a cylindrical sleeve 254 to an annular short-circuiting disc 252 fitted with spring tongues to make good contact with both the rod 242 and the cylinder 241. The thickness of the piston 256 and the length of the sleeve 254 are such that the gaps thus formed are effectively a quarter-wave long, and a low impedance is produced at the points 262, 263. Specification 612,406, [Group XL (c)], also is referred to.