GB592398A - Improvements in or relating to impedance transforming devices - Google Patents

Abstract

592,398. Microwave couplings. WESTERN ELECTRIC CO., Inc. Dec. 7, 1943, No. 20478. Convention date, March 26, 1942. [Class 40 (iii)] A wide-band microwave impedance-matching coupling for connecting an unbalanced circuit 5, 6 to a balanced circuit 4 comprises a double wave-guide structure 17, 13, 14. The coaxial line 5, 6 having a grounded outer conductor 6 feeds oscillations from a source 1 to a connecting chamber, 17 through an aerial element.22 formed by an extension of the inner conductor 5. The exposed length of the latter is regulated by means of an adjustable sleeve which thus. constitutes a multi-frequency device for matching the input impedance of the chamber 17 to the characteristic impedance Z /2 of the line 5, 6. The energy then divides through the two halves of chamber 17, each of characteristic impedance Z, into the four legs, each of impedance Z/2, of the loop sections 13, 14 and then passes through the feeders 8, 9, each . of which has an impedance Z /4 so that an impedance Z /2 faces the outgoing balanced line 4. The outgoing feeders are connected to opposite faces of the loops 13, 14, in order that the polarization may be such that the cores 8, 9 are excited in opposite phases with respect to the earthed sheaths 10, 11. The wave-guides 13, 14 may be folded in the plane of their depth, Fig. 2 (not shown), instead of that of their breadth, Fig. 1, and may be so twisted that the feeders 8, 9 have to be connected on the same side of the structure instead of as in Fig. 1. In a further modification, Fig. 3 (not shown), one of the loops 13, 14 may lie over and parallel with the other.