GB599804A - Adjusting means for electrical transmission lines - Google Patents

Abstract

599,804. Electric resonators. PHILCO RADIO & TELEVISION CORPORATION. Nov. 16, 1944, No. 22701. Convention date, Nov. 17, 1943. [Classes 40 (iii) and 40 (v)] A coaxial transmission line is electrically lengthened, without the introduction of impedance-mismatch, by the insertion of an adjustable section suitably dimensioned. Thus in a length-adjusting device of the trombone type, the incoming and outgoing lines 8, 9 are each coupled through a quarter-wave section 6, 7, to a sliding section 4, and the characteristic impedance of the coupling sections 6, 7, is the geometric mean of those of the sections 4 and 8, 9. The inner conductor of the sliding section 4 passes inside, and its outer conductor outside, the corresponding conductors of the coupling sections 6, 7, so that the length and characteristic impedance of the latter remains constant in spite of the adjustment of the sliding section 4. A straight section may be similarly constructed, Figs. 2, 5 (not shown). The device may be used in the feeder between a television transmitter and a dipole aerial, Fig. 1 (not shown).