Patent GB-228579-A (GB)
Title: Devices for exactly determining the direction of magnetic or electro-magnetic fields of low, medium or high frequency relatively to a direction in space
IPC: G01S1/02
Filed: 1923-08-07
Abstract: 228,579. Loth. W. A., and Soc. Industrielle des ProcÚdÚs W. A. Loth. Aug. 7, 1923. Directive signalling; inductive telegraphy; aerials and like radiating and receiving conductors.-In the instrument for determining the direction of magnetic and electromagnetic fields &c., described in Specification 195,088, the armature turns, frames, or elementary windings are separated one from another, or by groups, by breaks in continuity formed between blocks &c. so arranged that the turns can be connected either in series, parallel, or in series groups connected in parallel. In the construction shown in Fig. 1, one end 34 of each group of turns 2 is connected to a collecting-ring 35 of known resistance, the opposite ends 36 being connected to a second ring 37. Brushes 4, insulated from each other, rub on the ring 35 and are connected either directly or indirectly, with a tuned or other circuit, to a receiver 21 with or without an amplifier 29. Brushes 3 carried by a conducting bar 38 rub on the ring 37. The bar 38 may be in one piece or divided and having a second receiver connected between the brushes 3. The brushes 3, 4 may be parallel or at right-angles with one another. The ring 35 may be replaced by turns of bare resistance wire over which the brushes 4 slide. In an alternative construction shown in Fig. 3, the ends of the armature turns 2 are connected to contact-pieces 10 insulated from one another, the other ends of the turns 2 being connected together by a conducting ring. On the contact-pieces 10 rests a collecting-ring 5, 6, which can slide on them by rotation. The ring 5. 6 is cut at two points 43, 44, the gaps being filled with insulating material. Receivers or, as shown, primaries 45, 46 of a transformer are connected across the gaps 43, 44. These primaries may coact with a single secondary winding 47 connected to a receiver 21. By rotation of the ring 5, 6 the positions of maximum and minimum reception may be determined. More than two gaps may be formed in the ring 5, 6, for example four gaps at 90‹ to each other. The turns 2, instead of being wound on a solid core, may be supported in space by a mast and insulated supports or insulated wire stretchers. Each group of turns on the armature may be tuned by a condenser. Fig. 5 shows a further modification in which each turn or group of turns of the armature winding is cut at a point and the ends connected to insulated contacts 50, 51, or simply inserted into an ebonite ring so as to project slightly from the surface. An insulating ring 53, carrying as many conducting strips 54 as there are pairs of contact-pieces, is rotatably arranged on these contact-pieces. Two diametrically opposite strips are cut so as each to comprise two insulated portions 55, 56 connected to external contacts 59, 60, 61, 62. Assuming an alternating magnetic field in the direction of the arrow 58, and the contact-pieces 55, 56 in the position shown, no current flows in conductors 64, 65 connecting the points 60, 61 and 59, 62, but a maximum reception is obtained in a conductor 63 connecting the points 59, 60 and 61, 62. These conditions are reversed if the ring 53 is rotated through 90‹. Each turn of the armature winding may be wound in one plane, in which case the connecting strips 54 are inclined. Instead of angularly moving, the ring 53, pairs of diametrically opposite strips 54 may be lifted out of contact successively, the current receivers being connected to the lifted pairs so as to determine the points of maximum and minimum reception. Resilient contacts may be lifted successively by moving a diametral arm which is interposed between the bridging-strips and the contacts or between the two end contacts of the turns and carrying at its ends the pairs of insulated contact-pieces connected to the receiving system. The contact-pieces may be pressed together by springs and successively separated by the interposition of insulating tongues, or the bridging strips may move radially. In order to act simultaneously on a. number of armature turns an arm 57, Fig. 9, having tongues or cams 66 of greater circumferential length than that separating the two pairs of adjacent contact pieces, may be employed. This arm may be in the shape of a pair of scissors, the corresponding branches being connected by a portion of an extensible circle. The ends of the groups of turns thus separated from the armature are connected to the receiving apparatus. Fig. 10 shows a further modification in which loops 74 are connected in series with the individual armature coils and are arranged on an armature within which can rotate small coils 73 connected to the receiver. Small armatures similarly connected may be used for neutralizing the effects of parasitic fields on ships &c., and may replace the side horizontal receiving frames used in combination with vertical frames for guiding ships. The inclination of the field acting on each armature is thus found, enabling a leader cable to be located. For the same purpose two armatures bne at each side of the ship, having two identical frames at right-angles to each other may be employed. Each frame is connected to a small coil, and within these coils at right-angles to each other a third small coil rotates and is connected, through an amplifier or not, with the receiver.