GB1211726A - Loop antenna - Google Patents

Abstract

1,211,726. Aerials; radio direction finders. LTV ELECTROSYSTEMS Inc. 3 Nov., 1967 [9 Dec., 1966], No. 24664/70. Divided out of 1,211,723. Headings H4A and H4D. A cross-loop type aerial comprises a closed core 30, Fig. 3, of ferromagnetic material, formed by two pairs of parallel rods 31, 33 and 32, 34 upon which are wound respective pairs of coils 35, 36 and 37, 38. Each pair of coils is so connected that magnetic fluxes due to incident radio waves produce voltages which are additive, whereas the magnetic fluxes induced by a current flowing in the coils are opposed. The two coils may be of opposite hands and have their finish ends connected together (Fig. 1, not shown) or they may be of the same hand and have the finish end of one connected to the start end of the other (Fig. 2, not shown). As described, the two pairs of rods are of equal lengths and are disposed at right angles to each other, and all coils are of identical electrical dimensions. The output at terminals A, B from the pair of coils 35, 36 is independent of the output at terminals C, D from the pair of coils 37, 38, and the two outputs are effectively in quadrature. As shown in Fig. 3, the outputs are applied through conventional circuitry for omni-directional Loran- A reception. In another application, the outputs are fed to the orthogonal fixed windings of the resolver or goniometer of a directionfinding system which may comprise automatic tracking in association with a gyroscopic compass system. In a mounting structure for the aerial shown in Fig. 3, foamed plastics sheets 80, 81, Fig. 5, fill the centre of the core 30, and partially surround it. The sheets 80, 81 are clamped between two printed circuit board electrostatic shields 83, 84, which project beyond the core 30. The shield board 83 carries sockets 86, for fastening the assembly to its support, and conduit connectors 87, 88 for leads to the two pairs of coils of the aerial. A casting plastics material is applied on top of the shield board 83 and around the sockets 86 and connectors 87, 88 to form a plate 89. The same material is also applied between the projecting edges of the shield boards 83, 84 to form a collar 91. The screening strips on the shield boards 83, 84, which run radially to their edges, are connected together by strips 85. The structure is stated to be particularly suitable for mounting on aircraft and the like.