Abstract

A transmission line transformer (20, 30, 31) with inherent DC isolation has two sets (22, 22') of transmission line elements (ZN) with characteristic impedances which vary from relatively high values near the transformer inputs (P1, P2) to relatively low values near an intermediate location (28, 28') are ordered in a mirror image symmetry with respect to one another relative to the intermediate location (28, 28') in plural element embodiments (20, 30). The primaries (24, 24') are connected in series, while the secondaries (26, 26') of adjacent pairs of transmission line elements (ZN, ZN') are connected in series with the series connected pair connected in parallel across the output terminals (P3, P4). A center line transmission element (CZN) at the intermediate location (28') has a substantial zero impedance, and an electrical length equal to twice that of the other elements. In an embodiment (31) for the special case of N=1, the other transmission line elements of the two sets (22, 22') are eliminated and only a single center transmission line element (CZN) with approximately zero characteristic impedance is employed to obtain a broad band flat frequency response.