Patent GB-138586-A (GB)
Title: Improvements in the method of and in apparatus for receiving radio signals
IPC: H01Q1/00
Filed: 1919-05-22
Abstract: 138,586. Marconi Wireless Telegraph Co., (Assignees of Weaggnt, R. A.). Feb. 7, 1919, [Convention date]. Wireless signalling.-In order to prevent static interference in the reception of wireless signals, two aerial systems, or portions of an aerial system, are employed, one responding only to static waves, the other responding both to static and signal waves; and the oscillations due to static waves are balanced out by suitably combining the two systems. The method is based upon the theory relating to the nature of static disturbances described in Specification 132,548. The apparatus shown in Fig. 1 comprises two loop aerials A, 13 set up in the plane of the desired reception and separated by a considerable fraction of a wave length. The loops are connected through reversing-switches Z, Z<2> and leads C to receiving apparatus situated midway between them. The aerials A, B are tuned bv condensers D in the loops, and by inductances Land condensers K at the receiving station, and they are coupled by coils F, F<1> to an intermediate circuit J coupled to the detector circuit. A third loop aerial E is coupled to the intermediate circuit by the coil O. In the preferred manner of using the apparatus, the variable inductances L and capacities K and the reversing-switches Z, Z<2> in the circuits of the aerials A, B are adjusted until the signal currents in the receiver are eliminated, and the aerials respond only to static. These static currents are then utilized to balance out the static received on the aerial E, leaving only the signals received on the latter to affect the receiver. In another form of apparatus, shown in Fig. 2, two aerials S, T extend in opposite directions in the form of long low loops, for example, three miles long and with the upper wire thirty feet and the lower wire fifteen feet above the ground. A linear oscillator W extends to a shorter distance, say three thousand feet, on either side of the receiving station X, and is arranged beneath the loops S, T or at one side. All the aerials lie in the plane in which signals are to be received. The loop aerials are connected through reversing-switches m to the fixed coils of a goniometer, the movable coil q of which is coupled to the linear oscillator W and to the detector Z. Variable inductances o may be inserted at about the mid-points of the upper wires of the loops, and tuning condensers and inductances are placed in series with the goniometer coils at the receiving station. In operation, the signals received in the loops S, T balance out, whilst the statics received in the loops neutralize the statics in the aerial W, leaving the signals received on the aerial W to affect the receiver. In another modification, shown in Fig. 3, two loop aerials 2, 3 are arranged one above the other, for example twenty-five teet apart, and the received signals being in phase are balanced out by a goniometer, the fixed coils 6, 7 of which are connected to the respective loops. The statics received on the aerials 2, 3 affect the movable goniometer coil 9, which is connected to one of the fixed coils 15 of a second goniometer. The other fixed coil 13 is connected to the aerial loop 12, and the movable coil 16 to the receiver. Statics received on the loop 12 are balanced by those received on the loops 2, 3 and only signals received on the loop 12 affect the receiver. The loops 2, 3, 12 may be connected in series in a single circuit, in such manner that signals received on the aerials 2, 3 neutralize each other whilst the statics received on the loops 2, 3 balance those received on the loop 12. The arrangement shown in Fig. 5 comprises a linear oscillator A, with centrally-placed tuning condenser and inductances, mounted on a support C which can tilt in a vertical plane about the pivot E, and can swing in an horizontal plane on a vertical pin F. A loop aerial G is coupled to an intermediate circuit L which is coupled to the receiver P and to the movable aerial A. The movable aerial is tilted in the plane of reception until the signals, coming from the direction Q, are not received. The statics received on the aerial A then balance out the statics received on the loop aerial G.