GB1446815A - Direction finding equipment with at least two antennae systems - Google Patents

Abstract

1,446,815 Radio direction-finders; aerials LICENTIA PATENT-VERWALTUNGS-GmbH 1 Feb 1974 [6 Feb 1973] 04846/74 Headings H4D and H4A A direction-finding equipment comprises at least two directional aerial systems, and a further aerial system the signals from which are indicative of deviations in the received waves from a pre-determined direction of polarization and/or a pre-determined angle of elevation. Said signals may be used as criteria for the operation of the equipment for direction-finding when said deviations are within acceptable limits. As described, two loop aerials R1, R2, Fig. 1, are disposed in vertical planes which are at right angles to each other. The further aerial system consists of two semicircular loop aerials R3, R4 which are located in a horizontal plane, and which are so interconnected that the voltages induced in them are added. A vertical sense aerial H is also provided. Outputs from the aerials R1, R2 are processed in units V1, V2 and are applied to the orthogonal deflecting electrodes A1, A2 of a cathode-ray tube (CRT). The voltages from the units V1, V2 are also fed to a summing element S, the voltage from the unit V2 being first shifted in phase by 90 degrees. The output from the elements S is independent of the azimuth of the incoming waves, and is fed to one input of a comparator K<SP>1</SP>. In the embodiment shown in Fig. 4, a common processing unit V3 is used for the signals from the aerials R3/R4 and from the aerial H, which are connected thereto in alternating sequence by a switch U under the control of a multi-vibrator M. In the one position of the switch U a voltage due to the signal from the aerials R3/R4 is compared with the output voltage from the summing element S. If the amplitude of the signal from the aerials R3/R4 is sufficiently less than that of the combined signals from the aerials R1, R2, an electronic switch W is operated, and so biases the control grid G of the CRT as to brighten the display. In the other position of the switch U a voltage due to the signal from the sense aerial H is connected through directly to the control grid G of the CRT. It can only be effective if the switch W triggers said grid, and with suitably selected switch times the half of the CRT image which corresponds to the (incorrect) azimuth offset by 180 degrees appears substantially darker. In another embodiment (Fig. 3, not shown) separate processing units are provided for the signals from the aerials R3/R4 and H. The output from the processing unit associated with the aerial H is coupled through a capacitor to the control grid of the CRT. In another embodiment (Fig. 2, not shown) the sense aerial is omitted.