Method and apparatus for stabilizing pulsed microwave amplifiers

Apparatus for stabilizing the output of an electron beam driven pulsed microwave amplifier which has an input for receiving a low power microwave signal that is to be amplified and an output for delivering periodic output pulses of amplified microwave energy to a load, said low power microwave signal being produced by a low power microwave generator and wherein means for transmitting microwave signals couples said generator to said, input of said pulsed microwave amplifier, wherein the improvement comprises:

• first sensing means for sensing at least one characteristic of said low power microwave signal and which produces a reference signal that is indicative of said characteristic,
• second sensing means for sensing said characteristic in said amplifier output pulses and which produces output signals that are indicative of said characteristic in said amplifier output pulses,
• comparing means for comparing each of said output signals with said reference signal to produce a sequence of error signals that are indicative of variations of said characteristic at said pulsed microwave amplifier output during individual ones of said amplifier output pulses,
• means for storing a correction signal that includes said error signal during each of said sequence of said amplifier output pulses, and
• means for utilizing the correction signals which were stored during prior amplifier output pulses to modify said characteristic in said low power microwave signal during subsequent output pulses to suppress said variations during said subsequent output pulses.

Apparatus for suppressing phase variations at the output of a pulsed microwave amplifier during individual output pulses, said pulsed microwave amplifier being of the electron beam driven type and having an input at which a low power microwave signal that is to be amplified is received from a microwave generator through a low power microwave signal path, comprising:

• a voltage controlled variable phase shifter coupled into said low power microwave signal path,
• a phase difference detector having a first input coupled to said low power microwave signal path and a second input coupled to said output of said pulsed microwave amplifier and having a pair of outputs which exhibit a voltage difference that is a function of the degree of phase error at said pulsed microwave amplifier output relative to said low power microwave signal.
• a phase correction signal storage coupled to said phase difference detector and having means for storing a plurality of momentary values during the course of each output pulse of said pulsed microwave amplifier which momentary values are indicative of the value of said voltage difference at successive different times in the course of said output pulse combined with the momentary value that was stored at the corresponding time during a preceding output pulse,
• for sequentially reading out the previously stored momentary values during each output pulse in the form of a series of successive voltage levels which jointly provide the control voltage for said voltage controlled variable phase shifter, and
• means for transmitting said control voltage to said voltage controlled phase shifter during each of said output pulses.

Apparatus for suppressing amplitude variations at the output of a pulsed microwave amplifier during individual output pulses, said pulsed microwave amplifier being of the electron beam driven type and having an input at which a low power microwave signal that is to be amplified is received from a microwave generator through a low power microwave signal path, comprising:

• a voltage controlled amplitude modulator coupled into said low power microwave signal path,
• an amplitude difference detector having a first input coupled to said low power microwave signal path and a second input coupled to said output of said pulsed microwave amplifier and having a pair of outputs which exhibit a voltage difference that is a function of the degree of amplitude error at said pulsed microwave amplifier output relative to said low power microwave signal,
• an amplitude correction signal storage coupled to said amplitude difference detector and having means for storing a plurality of momentary values during the course of each output pulse Of said pulsed microwave amplifier which momentary values are indicative of the value of said voltage difference at successive different times in the course of said output pulse combined with momentary value that was stored at the corresponding time during a preceding output pulse,
• means for sequentially reading out the previously stored momentary values during each output pulse in the form of a series of successive voltage levels which jointly provide the control voltage for said voltage controlled variable signal attenuator, and
• means for transmitting said control voltage to said voltage controlled amplitude modulator during each of said output pulses.