GB673658A - Improvements relating to electrical coupling arrangements - Google Patents

Abstract

673,658. Aerial coupling arrangements. ELECTRIC & MUSICAL INDUSTRIES, Ltd. March 9, 1950 [March 9, 1940], No. 6365/49. Class 40 (v). In an electrical circuit arrangement including a feeder comprising an unscreened pair of parallel conductors connected at one end to a balanced device and at its other end to an unbalanced device, the conductors of the feeder are coiled together adjacent their point of connection with the unbalanced device in such a manner that balanced potentials at the balanced device are converted into unbalanced potentials at said point or unbalanced potentials at said point are converted into balanced potentials at the end of the coiled feeder remote from said point. As shown, a balanced device 1 which may be a dipole aerial is coupled to an unbalanced device 2, for example a radio receiver, via conductors 3 and 4, the ends adjacent device 2 being coiled together to provide a pair of coupled inductances, and optimum energy transfer is obtained if the electrical length of the coiled portion of each conductor is equivalent to an odd number of quarterwavelengths at the transmitted frequency. In some cases improved results may be obtained by spacing the coiled parts from the unbalanced device by a length of uncoiled conductor a quarter-wavelength long. In Fig. 2 (not shown) unbalanced potentials at an unbalanced device are converted into balanced potentials for transmission along an uncoiled portion of line and then converted to unbalanced potentials for feeding a further unbalanced device. Speci. fications 493,758 and 670,340 are referred to.