GB734161A - Improvements relating to high-frequency multi-layer conductors consisting of alternate thin layers of metal and insulation - Google Patents

Abstract

734,161. Conductors. SIEMENS & HALSKE AKT.-GES. Sept. 11, 1953 [Sept. 13, 1952; Sept. 15, 1952; Sept. 20, 1952 ; Sept. 20, 1952; Sept. 25, 1952; Dec. 15, 1952], No. 25228/53. Class 36. In a high-frequency multi-layer conductor consisting of alternate thin layers of metal and insulation, at least the metal layers extend helically and are preferably so arranged that the conductor is free from magnetic longitudinal fields or is rendered free from such fields by additional equalizing means. The metal layers 11, 12 inside and outside the zero current layer 10 may be given the same helical direction and suitable pitch angles so that equal but oppositely directed longitudinal fields are produced inside and outside the layer 10. The conductor parts 11, 12 may each consist of a number of subsidiary layers having different directions of twist and different pitch angles. which are selected to give the desired effect, or they may consist of a number of multi-layer conductor components each having a sectorshaped cross-section and assembled so that the inner and outer components have the same direction of twist. A cable may comprise two such multi-layer conductors coaxially disposed and separated by an insulating layer which may also contain conductive screen layers. The conductor may alternatively comprise a number of sector-shaped components twisted about a core, the direction of twist being varied at short intervals. The longitudinal field may alternatively be compensated by connecting together manufactured lengths of conductors having equal and opposite fields as determined by measurement. A multi-layer conductor may be produced from metal and insulating foils disposed over each other and wrapped about a core 50 with a long lay. The width of the foils increases from the inside towards the outside of the conductor 51 so that a narrow helical groove 51<1> is formed which increases in width towards the outside to permit bending of the conductor. An outer part 53 for the conductor is similarly formed, but the outer foils thereof result in a longitudinal magnetic field outside the conductor which may be compensated for by foils 54, which may consist of alternate insulating and metal foils applied with the opposite direction of lay. A multi-layer conductor may also be produced by winding conductive and non-conductive ribbons 69, 60 alternately on to core 61 in overlapping or abutting convolutions. The overlapping edges of the ribbons may be shaped to obtain uniform laminations and finally soldered or welded together. Alternatively, each metal layer may consist of two metal foils, preferably wound in opposite directions, the width of each foil being proportional to the diameter of the foil winding so that they may be wound with the same pitch angle, or metal foils lined with insulating material may be wound in pairs having the metal layers facing one another, alternate layers having the same or opposite direction of lay, or insulating foils coated on both sides with metal may be employed. A multi-layer conductor suitable for use as the inner and/or outer conductor of a coaxial cable may be formed from stranded layers of metal foil separated from each other by insulation having a low dielectric constant such as foam material. The insulation between the conductors may be solid or air-space. The inner conductor may comprise composite foils stranded on to a hollow core 80 to form layers 83, 84, 85, 86, having alternately opposite directions of lay. An insulating foil 87, spacing discs 88 and insulating foils 92, 93 are then applied and the outer conductor comprising layers 94, 95, 96, 97 formed in the same way as the inner conductor from composite foils. Insulating windings 98, 99 and water-tight sheathing 100 complete the cable. Specification 734,160 is referred to.