Patent GB-638297-A (GB)
Title: Improvements in or relating to directional radio systems
Inventor: STOKES VICTOR OWEN
IPC: H01Q3/34
Filed: 1947-04-21
Abstract: 638,297. Automatic phase control systems. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. April 21, 1947, No. 10628. [Class 38 (iv)] [Also in Groups XXXVI and XL (c)] A directional radio system comprises a plurality of aerial elements comprising a directional array fed by separate feeders from a common transducer, coupling means being introduced into at least all but one of the feeders including a resonant circuit having associated with it a reactance valve so that by varying the operating conditions of said valve or valves, the relative phasing of the aerials may be varied and the directivity of the system thereby adjusted. The system may also include one or more phase discriminators coupled to each adjacent pair of feeders and producing an output proportional to the relative phase of the currents therein which may operate a circuit associated with the reactance valve or valves controlling the feeders so that a predetermined directivity can be automatically maintained. In a' system having two aerial elements A and A<1> and fed from a master oscillator MO, the feeders F and F<1> each include an amplifier TA and TA<1> and a control circuit. The control circuit for the aerial A is fed directly by the oscillator MO and comprises a tuned circuit 3 across which is coupled a reactance valve 4. The output of the tuned circuit being fed through amplifier valve 2. The bias voltage fed over line 14 to the grid of valve 4 determines the phase 'shift introduced by the control circuit. The control circuit for the second antenna A<1> is similar to that for A except that it is fed from transformer 13 in the anode circuit of the valve 2 in the first control circuit. In arrays with more than two antennae it is preferred to feed each antenna from the output of the control circuit of an adjacent antenna. The grid lead 14 is connected to the mid-point of a potentiometer 16 connected across a bias voltage source 17. The equivalent lead 14<1> may be connected by switch 18 to a manually-adjustable tap on potentiometer 20 which may be experimentally calibrated in beam bearing angles. In the other position of switch 18 the voltage applied to lead 14<1> and indicated by meter 30 is derived from a tap on potentiometer 25, both ends of which are taken through resistors to the tap on potentiometer 16. Lines are also taken from the ends of this circuit to phase discriminator PD (see Group XXXVI) coupled to the aerial ends of the feeders F, F<1>, the output of which creates a potential difference between the leads 14 and 14<1> dependent on the tapping point on potentiometer 25. Any variation of this output due to changes in phase between the feeder signals produces a corresponding correcting variation in potential difference between leads 14, 14<1>, automatically correcting the variation. To oscillate the beam over a certain arc, switch 18 is set to its manual position and potentiometer 20 adjusted for the mid-point of the arc; then an alternating voltage of the required amplitude and scan frequency applied in series with this bias. A block diagram illustrating the use of the invention for reception is given at Fig. 2 (not shown).