Patent GB-594348-A (GB)
Title: Antenna array
IPC: H01Q3/30
Filed: 1944-08-04
Abstract: 594,348. Radio direction - finding. STANDARD TELEPHONES & CABLES, Ltd. Aug. 4, 1944, No. 14970. Convention date, Aug. 9, 1943. [Class 40 (v)] [Also in Group XXXV] A directional radio receiving system having a directivity variable in azimuth comprises a plurality of antennas arranged in a predetermined array and coupled to a receiver by similar number of transmission lines and associated phase changers for varying the magnitude of a voltage and simultaneously changing its phase through any angle between 0 degrees and 360 degrees. Each phase changer comprises a plurality of similar amplifiers, each including a thermionic valve with input control and phase control grids, reactive means included in the input circuits of the valves so that an input voltage applied to the phase changer is applied to the input control grids of the various valves with a maximum phase difference of less than 180 degrees, means for applying control voltages to the phase-control grids to vary the outputs of the respective amplifiers, and means for connecting the outputs of the amplifiers so that the output of the phase-changer is the vector sum of the voltage outputs of the amplifiers and is variable throughout the range 0 degree to 360 degrees. The antennas 1 ... 6, which are preferably aperiodic, are connected through impedances 50 to phase-change devices 8, 10 associated with each antenna. The phase-changers 8 are connected in pairs by lines 12 to points 16 which are further connected by lines 18 to a receiver 14. Control channels 31 ... 36 each comprising several conductors connect a phase control device 28 to the phase changers 8 and a similar control device 44 is connected by channels 37 ... 42 to the phase-changers 10 which are associated by lines 20 and 24 with a separate receiver 26. The array is capable of simultaneous reception of different frequencies from one direction or of a single frequency from different directions. A phase-changer shown in detail in Fig. 2 comprises three amplifiers A, B, C connected in parallel with the input impedance 50 associated with an antenna. The input is fed directly to the grid 52 of the amplifier A, with retardation to the grid 53 of amplifier B, and with phase advancement to the grid 54 of amplifier C, and inductance 56 and capacity 58 being included in the input circuits of the amplifiers B, C respectively. The outputs from the plate-cathode circuit of the amplifier A, B, C are connected at points 120, 122 to prove a vectorial addition of voltages with phase differences of approximately 120 degrees, the magnitude of the outputs of the amplifiers A, B, C being controlled from the phase control device through conductors 78, 104, 116 connected to auxiliary grids 76, 102, 112 and conductors 80, 106, 118 connected to the plates 70, 96, 114 of the amplifiers. The input, signals received by the antennas 1 ... 6 are applied with continuously variable and different phase shifts to the receiver 14 which is utilized to derive the direction of transmission from the phase-shifts applied to the signals received at the antennas 1 ... 6 by the phasecontrol device 28. An example described in connection with Figs. 3, 4 (not shown), relates to a binomial array includes numerical calculation of the requisite phase-shifts to be applied to the signals received by constituent antennas in order to determine when the transmission is being received from a prescribed direction. As shown in Fig. 5, the antennas are arranged in two concentric circles, members A1 ... A6 and A7 ... A12 of the outer and inner arrays being shown. The outer members are spaced apart by a distance equal to one half of the wavelength of the operating frequency and adjacent antennas are spaced 24 electrical degrees apart. Phase-changers as described in Fig. 2 and associated with the antennas are connected over channels 230 with phase control devices 232 and over lines 220, 222, with a receiver 274. The magnitudes and phases of the voltages to be applied from the phasechangers to obtain directivity in directions D1, D2 are indicated on Fig. 5, and are displayed graphically in Fig. 7 (not shown). A phasecontrol device for the circular array is shown in Figs. 10, 11. Three similar coaxial rings of segments X1... X15, Y1 ... , Z1 ... are connected through thermionic rectifiers D to the grids of amplifiers A, B, C respectively of fifteen phase-changers associated with the antennas of the outer array-a similar arrangement being necessary for the phase-changers of the inner array. Associated with the three rings of segments are shaped members X<1> Y<1> Z<1> mounted on a shaft 282 rotated by a motor 280. The members X', Y<1>, Z<1> form capacity couplings with the fixed segments and at any position provide the required biasses on the phase-control grids of the amplifiers A, B, C of the phase-changers. A high-frequency source 250 is coupled to the members X<1>, Y<1>, Z<1> through a brush 252, and a tank circuit 256, comprising a capacity 258 and inductance 260, is provided. The output of the receiver is applied to coils 270, 272, Fig. 11, associated with a cathode-ray tube 274 and rotated at the same speed as the shaft 282 so that the position of the directivity on pattern 284 on the screen determines the direction which which the received energy is being transmitted. Specification 591,854 is referred to.