GB614384A - Improvements in or relating to wireless direction-finding apparatus - Google Patents

Abstract

614,384. Directive radio systems. PANSTWOWE ZAKLADY TELE-I RADJOTECHNICZNE W WARSZAWIE. March 29, 1939, No. 9865. Convention date, April 15, 1938. [Class 40 (vii)] Relates to means for balancing out any horizontally polarized pick-up in an Adcock system with screened feeders. According to the invention, each of the feeders L1, L2, Fig. 1, for the two spaced aerials A1, A2 comprises an internal conductor a1 or a2 surrounded by and insulated from an external conductor which may comprise a tube b1 or b2 or two bars or plates connected together, the two external conductors being insulated from each other and from earth. The internal conductors are connected to the opposite ends P, K of the coupling coil L and each external conductor is connected to the end opposite to that to which its corresponding internal conductor is connected. To balance the system the relationship Cr C+0.5 Ca= 0.5 - must be satisfied where C w is the inter-aerial capacity, Ca is the equivalent capacity of the aerial-earth capacities Ca1 and Ca2, Cr is the equivalent capacity of the two external conductor earth capacities Cr1 and Cr2, and w is a co-efficient depending upon the distribution of the earth capacity of the feeders. This balancing may be performed by adjusting the length of the aerial conductors or by adjusting condensers in the leads between the external conductors and the coupling coil L (Fig. 3, not shown). In a modification, Fig. 4, the external conductors are connected to tappings 01, 02 on the coil which are symmetrical to the electrical centre of the coil, and in the equivalent arrangement in Fig. 5 the external conductors are connected to a separate winding L2<1> coupled to the coil L1<1>, the balance depending on the nature of the mutual coupling. In any of the arrangements described the mid-point of the coil L may be earthed and in order to prevent changes in the earth capacities of the system an earthed counterpoise may be provided consisting of a number of conductors buried in the ground radially with respect to the vertical axis of symmetry of the system. Balance is improved by placing the aerial feeders at an optimum height above the ground e.g. two metres. The invention is applicable to rotatable systems and to radio-goniometer systems.