Apparatus for the gated modulation of a radio-frequency carrier signal

Apparatus for the gated modulation of an RF carrier signal uses a balanced circuit for amplitude-modulating the carrier signal, and a circuit having a predetermined minimum on-off amplitude-ratio for providing respective very high attenuation and very low attenuation to the modulated carrier signal responsive to respective off and on levels of a binary logic gate signal. Each of the RF carrier, modulation and gate signals may be individually buffered and/or amplified prior to use of that signal in one of the modulation or gate processes. The modulated RF carrier signal and/or the gated RF signal may also be buffered and/or amplified prior to being respectively gated in, or output from, the apparatus. Each of the buffer-amplifiers, except the gate signal buffer-amplifier, may itself be gated responsive to the gate signal, to provide a desired degree of apparatus output signal on-off ratio.