Patent GB-134644-A (GB)
IPC: G01S1/02
Abstract: 134,644. Hinton, N. P., and Radio Communication Co. Nov. 22, 1918. Directive wireless signalling; bearings, determining wirelessly. - The direction of a wireless transmitting-station is determined by employing three, five, or more immovable directive aerials and comparing the signals received when the aerials are connected in series in various orders, or when the aerials are placed in circuit singly in turn. The aerial circuit may include a coil rotatably mounted in the field of three, five, or more secondary coils connected to the receiver, the connexions of the secondary coils being varied similarly to those of the aerials and by the same switch. The arrangement may be slightly modified for transmitting signals directively, and for determining the direction of a receiving-station with respect to the transmitter. Fig. II shows an arrangement of three aerials and a three-coil secondary, the diagrams (1), (2), (3) indicating the three different connexions of the aerials and secondary coils, and Fig. III shows the dial for indicating the direction. The three aerials AB, CD, EF are .symmetrically arranged about a common vertical axis, and are connected in series in three different orders to a divided coil H separated by a condenser G. The coil H is rotatably mounted in the field of three symmetricallyplaced coils LM, NO, JK which are connected in series in the same order as the aerials, and are also connected to the receiver. The three aerials connected as in (1) are the electrical equivalent of a single aerial in the plane CD, and the three coils connected as in (1) are the equivalent of a single coil in the plane LM. Similarly, the arrangements shown in (2) and (3) are equivalents of single aerials and coils in the planes EF and AB respectively. Instead of altering the connexions as shown in (1), (2), (3), the control switch may therefore in the position (1) put CD and LM in circuit and cut out the remaining aerials and coils, with corresponding connexions for positions (2) and (3). With the arrangement (1), a signal arriving from a direction making an angle Y with the aerial CD produces a current proportional to cos Y through the movable coil H If this coil is placed so that its axis makes ar angle Z with the coil LM, the signal strength in the receiving-circuit is proportional to cos Y cos Z When the connexions are changed to (2) the sig nal strength in the receiving-circuit is propor tional to cos (60-Y) cos (60-Z). The angle Z is adjusted until the signals are of equal strength and by equating the above expressions it is found that Y+Z= 60 degrees, and, as Z is known, Y may be readily determined. The coil H is con. nected to a. pointer, Fig. III, moving over a dial divided into sectors of 60 degrees. The position of the pointer giving maximum signals for the arrangement (1) is indicated by S', and the position for minimum signals by O<1>, with similar reference letters for the arrangements (2) and (3). In practice, the two arrangements giving the strongest signals, say connexions (1) and (2) of Fig. II, are alternated by means of a hand-switch, and the coil H is adjusted until the signals are equal, the reading of the pointer on the dial then indicating the angle Y. There are two positions of the switch and two positions S<1> on the dial corresponding to the arrangement (1), so that the signals for the positions (1) (2), or (2) (3), or (3) (1) may be readily compared. In a simpler form of apparatus, the aerials are connected directly to the receiving-circuit, the secondaries LM &c. being dispensed with. The order of strength of the signals, when the aerials are connected as in (1), (2), and (3) respectively, enables the direction of the signals to be determined within a 30 degrees zone. When the apparatus is used as a transmitter, a revolving switch may be arranged to connect the aerials as in (1), (2), (3) and (1) followed by a pause. Any receiving- station, by noting the relative strengths of the signals, could determine approximately its position relative to the transmitter. The transmitting-aerials may also be energized by a movable coil, such as H, from a three-coil primary similar to the secondaries LM &c. Signals are sent out alternately on two positions, say (1) and (2), of the control switch, and the coils H adjusted until the receiving-station reports equality of signals. The position of the pointer on the dial then indicates the direction of the receiving-station. Aeroplanes fitted with ordinary trailing aerials can maintain a definite line of flight by noting the order of signal strength; and, with two or more transmitting-stations using different wavelengths, an aeroplane or ship may determine its position absolutely.