GB573365A - Improvements in or relating to high-frequency transformers - Google Patents

Abstract

573,365. High-frequency transducers. COLLARD, J. June 3, 1941, No. 7042. [Class 40 (iii)] A transformer or transducer for high-frequency currents comprises a cylindrical conductor C a half-wave-length long and two inner conductors R1, R2 short-circuited by end-plates which are formed with central holes for the reception of lengths of coaxial cable CC terminating in short-circuiting loops L1, L2. There is thus a mutual coupling between each loop and the twin circuit formed by the conductors C, R1, R2 dependent on the protrusion of the loops into the interior of the cylinder and on their angular relation to the conductors R1, R2 and the arrangement is equivalent to the three-winding transformer in Fig. 3. The loops are split to introduce series capacities C1, C2, which are adjusted to tune out the selfinductances S1, S2 of the loops at the operating frequency. For efficient transfer of power,. the resistance R of the twin circuit should be as small as possible and the coupling as tight as possible. The length of the conductor C may be adjusted if necessary by means of a small screwed plug. The two inner conductors may be replaced by a single central conductor with the loops placed off-centre, or four spaced conductors may be used. The dimensions may be reduced if the cylindrical space is filled with a material of high dielectric constant. A variable attenuator may be formed by connecting a given length of cable to one of the loops.