Abstract: A four port coupler includes a first port adapted to impedance match to a first impedance Z.sub.o, a second port adapted to impedance match to a second impedance Z.sub.1 different than the first impedance, a third port adapted to impedance match to the first impedance and a fourth port adapted to impedance match to the second impedance.

Abstract: A biphase modulator without matching elements includes a Lange coupler (5) including first, second, third, and fourth ports (1,2, 3, 4), where the first port (1) receives a RF input signal. FETs (6, 7) each have a source, gate, and drain (19, 17, 18 and 22, 20, 21). The drain (18) of the first FET (6) is coupled to the second port (2), the source (19) of the first FET (6) and the second FET (7) are coupled to electrical ground, and the drain (21) of the second FET (7) is coupled to the fourth port (4). The FETs, are switched at the desired modulation frequency by a control input (16) to the gates (17, 20), alternately providing a zero volt signal and a pinch-off voltage signal which produces a biphase modulated RF input signal at the third port (3) of the Lange coupler (5).