Abstract: A circuit which modulates an r.f. carrier to produce an FM signal having a substantially linear frequency relation to an applied modulating voltage over a selected deviation bandwidth. An r.f. oscillator having an output matching circuit supplies the carrier to a modulator. The impedance of the oscillator is adjusted by the matching circuit to present a desired reactive mismatch to the modulator over the bandwidth. The modulator includes a pair of voltage dependent reactive impedance elements, oppositely biased and separated by a quarter wavelength line which acts as an impedance inverter. A modulating voltage applied to both of the elements causes a reactive imbalance therebetween, affecting either a net inductive or capacitive change in the load impedance presented to the oscillator. The center frequency of the circuit reacts in a substantially linear manner to the modulating voltage over the deviation bandwidth.

Abstract: Phase dispersion between two or more traveling wave tubes (TWTs) is corrected on a pulse to pulse basis by a feedback loop which compares the relative phase of RF signals to be amplified in traveling wave tubes with one another, and provides a phase correction at the input to at least one of the traveling wave tubes such that the phase difference at the output of traveling wave tubes is the same as the phase difference at the inputs thereto, except for any offset therein which may be purposely inserted as desired. The phase difference at the input and at the output is achieved by phase correlators feeding sample and hold circuits, the outputs of which are converted from rectangular coordinates to polar coordinates including an angle; the phase difference angle at the input being compared with the phase difference angle taken from the output.