Patent GB-822274-A (GB)
Title: Improvements in or relating to methods of manufacturing waveguides and waveguide components
Inventor: TRAFFORD RICHARD ALFRED NORMAN
IPC: B21C37/15
Filed: 1956-08-23
Abstract: 822,274. Making waveguides; sheet-metal joints; brazing; soldering. GENERAL ELECTRIC CO. Ltd. Aug. 23, 1957 [Aug. 23, 1956 (2)], Nos. 25855/56 and 25857/56. Classes 83 (2) and 83(4). [Also in Groups XL (b) and XL (c)] A method of making a waveguide or a waveguide component includes fitting together a plurality of metal members, bending, twisting or deforming portions of at least some of the said members so that the members are locked together and then joining contiguous members to form a unitary structure. A long slot waveguide coupler, Fig. 2, accompanying the first Provisional Specification, comprises two lengths of waveguide terminatiing with flanges 1, 2 and 3, 4 respectively. The top and bottom members 5, 6 of the coupler have holes 7 which receive tags 15 on the side members 9-13. After assembly the tags 15 are twisted through 45 degrees and end tags 16, 17 are bent to grip the flanges. The member 11 of commerciallypure aluminium is recessed at 21 and 22 to receive members 10 and 13 and also has two cut-away portions 23 with semi-circular edges which constitute the coupler slots. The flanges 1-4 are of aluminium-manganese alloy or aluminium-magnesium-silicon alloy. The remaining members are of an aluminium-manganese alloy coated on both sides with an aluminiumsilicon alloy. Alternatively the base may be aluminium-magnesium-silicon alloy with a coating as before. The assembled coupler is cleaned in sodium hydroxide, rinsed and dipped in nitric acid or may be degreased only, using trichlorethylene vapour. On immersing after preheating in a brazing flux for 15 seconds to 4 minutes at 580-640‹ C. the aluminium-silicon coating flows to braze the structure. The tags 15, 16, 17 may then be removed. Alternatively the members may be joined by welding or soldering. In a modification a flange 55, Fig. 2, accompanying the Complete Specification, is attached to a waveguide having members secured by twisted tags. The waveguide members enter milled slots 59, 60 in an annular portion 58 of the flange 55. The flange, which has a choke on the far side, is secured prior to brazing of the assembly by four pins 53 located in holes 64 and 65. The invention is also applied to a primary aerial assembly for an aerial system comprising a paraboloidal reflector and a rotatable primary aerial, which is excited by a coaxial line feeder projecting through the reflector. The aerial assembly, Fig. 2, accompanying the Provisional Application 25857/56, comprises two-part dipoles 31, 32 mounted on a member 44, which is secured to a tapered waveguide 33 having an end member 34 through which projects the coaxial line feeder. The member 44 is retained in slots 45 by centre punching. The waveguide members 35, 36, which may be dynamically balanced, are then connected by twisting tags 37. An iris member 40 is located by tags 39. The end member 34 is located, prior to brazing together of the assembly, by pegs 42 which engage holes 43. The member 48 projecting through the end member 34 is secured by a screw 49 or may be located by a plug in the end member until brazing secures it to the member 36. The members 34 and 48 are of an aluminium-magnesium-silicon alloy, the members 31, 32 and 40 are of aluminium and the member 44 is. of an aluminium-manganese alloy. Alternatively the dipoles may be of aluminium-magnesium-silicon alloy. The remaining members are of the coated construction already described. In modifications the tags connecting various components may be deformed either by shearing lengthwise or by squeezing. The waveguides or components may also be made from steel or brass. In a further modification two waveguide couplers may be connected together using common top and bottom members. If a length of waveguide is required to act as a variable attenuator a rectangular hole may be left in one wall into which may be screwed or soldered a block of metal supporting an adjustable resistive card. Specification 809,751, [Group XL (c)], is referred to.