a circuit capable of vector magnitude control and phase reversal for a radio signal such as an intermediate frequency signal . the circuit includes an inverting signal path and a noninverting signal path and means for selecting between the two . further , a variable attenuation controllable from a function control input establishes the magnitude of the output signal vector . there is also disclosed a phase shifter employing two such circuits . in the phase shifter , a radio signal vector to be shifted is applied to the inputs of the two circuits , with a 90 ° shift between the two inputs . with proper vector magnitude and phase reversal control of the two circuits , there can be provided a preselected phase shift in any quadrant .