Patent GB-1275174-A (GB)
Title: Improvements in or relating to directional antenna systems
IPC: H01Q3/26
Filed: 1970-05-22
Abstract: 1275174 Aerials; radio direction-finders SIEMENS AG 22 May 1970 [23 May 1969] 24784/70 Headings H4A and H4D A directional aerial system in the form of a planar array comprises a plurality of modules M which are arranged in mutually parallel rows and columns and which, as described, are mutually perpendicular, and may be spaced apart by half the wavelength at the mean operating frequency. The elements of the array are mutually decoupled, and each is connected to its associated signal terminals via a respective controllable delay line L, which may operate either at radio frequency or at an intermediate frequency (in the drawing the delay lines are shown for convenience as though separated from the modules). The signal terminals of the modules are interconnected so that separate outputs are obtained corresponding respectively to, (1) all modules in odd-numbered columns, (2) all modules in evennumbered columns, (3) all modules in oddnumbered rows, (4) all modules in even-numbered rows. The two output connections consequently required from each module may be decoupled by means of a hybrid junction. Outputs (1) and (2) are connected to respective inputs of a phase discriminator P1, and outputs (3) and (4) are connected to respective inputs of a phase discriminator P2. All four outputs are also connected via buffer amplifiers E to an input terminal A of a receiver. When an incident wave-front is parallel to the plane of the array, the outputs from the modules are co-phasal, and neither discriminator produces an output. If the wave-front is tilted in the direction of the rows (i.e., in the x-direction) there is a phase difference between the output (1) from the modules in the odd-numbered columns, and the output (2) from the modules in the even-numbered columns, and the phase discriminator P1 produces a control voltage which is positive or negative, depending upon the sense of the angle of tilt of the incident wave-front. The control voltage is applied via an amplifier V1 and a contact of an arm of a switch S to a potential divider chain formed by identical resistors R connected in series. From the potential divider chain an appropriate proportion of the amplified control voltage is applied to the delay lines of each column of modules, so that the delays change until the outputs are once again substantially co-phasal. Similarly, when the incident wave-front is tilted in the direction of the columns (i.e., in the ydirection) the phase discriminator P2 produces a control voltage which is applied via an amplifier V2 and a contact of the other arm of the switch S to a potential divider chain which is associated with the delay lines of each row of modules. The directional beam characteristic of the system is thus made to track or follow up. A search facility may be provided, scanning generators SG being connected to the two potential divider chains via other contacts of the switch. When a signal of sufficient amplitude appears at the terminal A, the switch S is restored to the contacts connected to the amplifiers V1, V2 by an automatic switching system B. The system may be used for transmission with either one array alternately receiving and transmitting, when each module comprises a transmitting and a receiving branch coupler, or with a separate array for transmitting, to the delay lines of which are applied control voltages of the receiving array. In the former case, control voltages obtained during the receiving phase are stored in a store C and may be called up for the direction represented upon a command to the switch S.