Abstract: A high-power relativistic magnetron wherein the cathode geometry is shaped to form a DC electric field that has a non-negligible azimuthal component causing preferential selection of the pi mode at startup (suppression of mode competition), a significant increase in radiated power output and time integrated efficiency when compared to standard relativistic magnetron cathode designs.

Abstract: A pulsed magnetron is caused to emit a series of RF energy pulses which are phase coherent with an injection signal by supplying the magnetron with a pedestal pulse during low-power signal injection. The pedestal being of a magnitude and duration such that the slow-rise-time pedestal portion holds the magnetron in the Hartree region during the signal injection.

Abstract: The invention provides a magnetron drive circuit which drives a magnetron to produce a generally rectangular-shaped narrow transmission pulse having sharply shaped rising and falling edges. The magnetron drive circuit includes a nonlinear load circuit and an active damper circuit. The nonlinear load circuit becomes on at around 80% of a peak output voltage of a pulse transformer (at which the magnetron begins to oscillate) is connected to a secondary winding of the pulse transformer in parallel with the magnetron. The active damper circuit absorbs residual energy left in the pulse transformer without any need for an absorption resistor conventionally connected between both ends of a primary winding of the pulse transformer.

Abstract: The microwave pulse generator of the invention for generating microwave pulses with a pulse duration in the nanosecond range has a pulse generator that generates pulses of constant width, and a microwave resonant circuit for generating microwave oscillations. Additionally provided is a pulse-shortening stage, to which the pulses from the pulse generator are fed and which generates output pulses in the nanosecond range. The output pulses are fed as supply voltage pulses to a microwave oscillator, at the output of which the microwave pulses can be picked off. A voltage-controlled varicap diode arrangement is provided to influence the pulse lengths and/or pulse amplitudes.

Abstract: A high voltage pulse generation device for magnetron is disclosed. The device is divided into a DC voltage generation part, which continuously applies a variable DC voltage at a constant value to the load, and a pulse voltage generation part, which generates a momentary high voltage pulse and supplies the same to the load. The voltage applied to the load is a superposition of the output voltages from the two devices. Further, a pulse transformer demagnetization power supply is provided. A high voltage pulse waveform is obtained by momentary resonance and the pulse transformer using a low voltage at the time of pulse generation, thereby reducing the insulation space required and the size and the weight of the device. It is also possible to adjust the peak value and pulse cycle of the DC voltage applied to the load in addition to the pulse voltage.

Abstract: A first magnetic flux field is produced in the vicinity of a generally cylindrical pulse generating coil arrangement and a plasma is abruptly and radially displaced outwardly toward the coil arrangement, which in turn displaces the first magnetic flux field to a sufficient degree to enable it to cut across the output coil to generate an output pulse. Displacement of the plasma is effected by producing a second magnetic field transverse to the direction of the first magnetic field and to the direction of current within the plasma by means of a longitudinal, centrally positioned conductor coupled to a source of electrical power.

Abstract: An improved low power pulsed anode magnetron is provided having a cylindrical cathode centrally disposed within a plurality of radial anode vanes. An interaction region is provided between the surface of the cathode and the anode vane tips. A ratio of the anode-to-cathode space over the center-to-center distance between adjacent vane tips is within a range between 0.95 and 1.05. The cathode is joined to a magnetic polepiece assembly which channels magnetic flux to the interaction region. Both the cathode and the polepiece are mechanically adjustable from external to the magnetron to reposition the cathode and polepiece with respect to the anode vanes. The cathode surface is formed from an active nickel alloy which is cleaned by a chemical process followed by a high temperature and vacuum firing. An emissive surface is applied over the cleaned cathode surface.

Abstract: A semiconductor diode is connected across the cathode-to-anode path of a magnetron and through a storage capacitor and collector resistor to a supply voltage for enabling charging of the capacitor. A control pulse causes a switching transistor to conduct to discharge the capacitor through its collector-to-emitter path, an emitter resistor, and the magnetron, for causing the latter to oscillate. A feedback signal representative of the difference between the magnetron output frequency and a reference frequency is applied to a linear amplifier transistor which conducts through the emitter resistor for controlling the current flow through the switching transistor and the operating frequency of the magnetron.

Abstract: A switched-inverter modulator for use in driving a load that comprises master and slave high voltage power supplies for providing output pulses that directly drive the load. A synchronized pulse generator provides pulse width tinting and synchronized amplitude commands to the master power supply. The timing pulse instructs the power supplies when to initiate high voltage and for what time interval. The analog waveform instructs the master power supply as to what high voltage level to obtain. The master power supply may have multiple slaves connected in parallel for additional current capacity. A low voltage DC capacitor bank is connected in parallel with each of the power supplies to supplement energy storage. Isolation resistors are coupled between outputs of the respective high voltage power supplies and the load to minimize temporary shorts from ringing back into the power supplies.

Abstract: A modulator for providing modulating voltages across the anode and cathode of a negatively pulsed magnetron includes a switch which, when activated, couples the modulating voltage source to the cathode terminal, a current regulator which maintains a constant current flow through the anode and cathode when the modulating voltage is applied, and a voltage control circuit that reduces an excessive time rate of voltage change across the switch caused by arcing across the anode-cathode gap. A filament power supply is provided which supplies filament current while isolating the modulating voltage at the cathode from high voltage sensitive components in the filament power supply.

Abstract: A power supply circuit for a magnetron adapted to supply microwave energy to an electrodeless discharge bulb is disclosed. The circuit includes a rectifier coupled across a commerical AC voltage source, a filter for smoothing the output of the rectifier, an inverter for converting the DC voltage supplied from the filter into a high frequency AC voltage, a step-up transformer for stepping up the high frequency AC voltage outputted from the inverter, and a rectifier which rectifies the high voltage AC output of the transformer into a unidirectional voltage which is supplied to the magnetron. The inverter switching is controlled by a pulse width modulation control circuit to maintain the magnetron output power at a predetermined level.

Abstract: A power supply circuit for a magnetron adapted to supply microwave energy to an electrodeless discharge bulb is disclosed. The circuit includes a rectifier coupled across a commercial AC voltage source, a filter for smoothing the output of the rectifier, an inverter for converting the DC voltage supplied from the filter into a high frequency AC voltage, a step-up transformer for stepping up the high frequency AC voltage outputted from the inverter, and a rectifier which rectifies the high voltage AC output of the transformer into a unidirectional voltage which is supplied to the magnetron. The inverter switching is controlled by a pulse width modulation control circuit to maintain the magnetron output power at a predetermined level.

Abstract: A power supply circuit for a magnetron adapted to supply microwave energy to an electrodeless discharge bulb is disclosed. The circuit comprises a rectifier coupled across a commercial AC voltage source, a filter for smoothing the output of the rectifier, an inverter for converting the DC voltage supplied from the filter into a high frequency AC voltage, a step-up transformer for stepping up the high frequency AC voltage outputted from the inverter, and a rectifier which rectifies the high voltage AC output of the transformer into a unidirectional voltage which is supplied to the magnetron. The inverter switching is controlled by a pulse width modulation control circuit to maintain the magnetron output power at a predetermined level.

Abstract: In a power-line-operated inverter-type magnetron power supply having a high-Q resonant L-C circuit series-excited by the inverter and parallel-loaded by the magnetron, subject invention provides for cost-effective means to prevent the destructive overload of the inverter and/or the L-C circuit that may occur during the brief period before the magnetron cathode becomes incandescent. In this power supply, the unfiltered pulsed DC output of a full-wave power-line-supplied rectifier means is applied to a pair of inverters: an auxiliary inverter for heating the magnetron cathode, and a main inverter for providing the main magnetron power. The auxiliary inverter starts operating immediately upon application of power from the power line, and therefore immediately starts the process of cathode heating.

Abstract: In a magnetron having a rotatable tuning member in the form of a spinner (121), a rotation sensor and an associated processor (10) generates an indication signal (11) representing the instantaneous magnetron frequency. Three level discriminators 13(1), 13(2), 13(3) are arranged to compare the indication signal (11) with respective threshold signals 14(1), 14(2), 14(3) representing different, preset frequencies. The level discriminators produce a trigger signal T effective to initiate transmission of a pulse of radiation whenever the instantaneous magnetron frequency matches one of the preset frequencies.

Abstract: In a power-line-operated electronic inverter-type power supply for the magnetron in a microwave oven, the unfiltered pulsed DC output of a full-wave rectifier is applied to a bridge inverter, the output of which is a 30 kHz squarewave voltage pulse-amplitude-modulated at 120 Hz. By way of a step-up voltage transformer, this 30 kHz output voltage is applied to a high-Q series-resonant L-C circuit. The Q-multiplied voltage developing across the tank capacitor of this L-C circuit is then rectified and filtered for 30 kHz ripple-voltage. The output resulting from this high-frequency rectification is a 120 Hz pulse-amplitude-modulated current-limited DC voltage suitable for direct application to the magnetron. The bridge inverter has to be triggered into oscillation; which oscillation ceases each time the magnitude of the inverter DC supply voltage decreases below a given threshold level.

Abstract: A duty cycle power control circuit for a magnetron including a power transformer having a primary winding, a secondary anode winding for supplying anode voltage to the magnetron and a secondary filament winding for energizing the filament of the magnetron. In the illustrative embodiment the power transformer primary winding comprises a main winding and a serially connected standby winding. Duty cycle controlled switching devices are effective in a standby state to connect the main winding in series with the standby winding across an external power supply and are effective in the power on state to disconnect the standby winding and connect the main winding directly across the external power supply.

Abstract: A circuit for generating high frequency output pulses comprising a magnetron, a pulse transformer having its secondary winding coupled to apply firing pulses across the input terminals of the magnetron, charge storage means connected in circuit with the primary winding of the pulse transformer, and switching means for discharging the charge storage means through said primary winding to generate a firing pulse from said secondary winding, said switching means comprising an FET switching device having output terminals connected in series with said primary winding, and a control terminal, and a control circuit adapted to deliver low voltage (e.g. less than 20 volts) pulses to said control terminal.

Abstract: A pulse circuit forms part of a radar transmitter in which a pulse forming network is used to generate a high current pulse at relatively low voltage and to feed it via a transformer to a magnetron which operates at typically 30 kV. A number of pulse forming networks are connected in parallel and are discharged by respective thyristors. The outputs of the pulse forming networks are combined so as to provide a low voltage pulse (of the order of 600 volts) having sufficient power to drive a radar transmitter. The pulse forming networks must each be capable of handling very large current and must have characteristics which are identical to each other. To enable these requirements to be met, each pulse forming network includes an inductor which is formed as a coiled thin conductive layer lying on the surface of an electrically insulating board. It is formed by printed circuit board techniques and a mirror image coil is formed on both sides of a double sided printed circuit board.

Abstract: A zero-crossing signal is generated in response to the zero-crossing of the current of an AC power source of a magnetron oscillator, and in response to the zero-crossing signal a triac connected between the magnetron oscillator and the AC power source is turned on to generate a microwave. The triac is turned off when the voltage of the AC power source becomes lower than a holding voltage of the triac.

Abstract: A power supply for controlling the duty-cycle of a microwave oven magnetron and the like power-energizing load, includes a parallel combination of a non-linear resistance element, such as a varistor and the like, and a gateable semiconductor switching device, such as a triac and the like, in series with a power supply voltage-doubler diode, connected in parallel across the magnetron. The flow of current through the magnetron is substantially reduced or prevented when the semiconductor switching device is gated to an "off" condition and is substantially enabled to a normal current flow value when the semiconductor switching device is gated to an "on" condition, typically by high frequency squarewaves provided at the gate electrode.

Abstract: A radar system having automatic compensation to the heater power applied to the final output tube for changes in the peak tube power output. Substantially constant peak power is attained for radar pulses of varying widths and over a plurality of range scales. A controlled voltage is derived in accordance with the peak of the anode power or current coupled to the final transmitter tube. The control voltage is amplified to operate a free-running bistable multivibrator the output of which is transformer coupled to the heater of the output tube.

Abstract: An active radar transmitter is disclosed having both long pulse and short lse operational modes. The transmitter is configured to switch between the operational modes with a minimum of circuitry to permit a single radar system to be used for long-range search and short-range, high resolution search.

Abstract: A magnetron transmitter having a two-stage modulator, one stage generating long, slowly rising, low power pulse, and the other generating a short, high power pulse, whereby high resolution is obtainable without the use of pulse compression techniques.

Abstract: In a microwave energy generating system, a combination of a magnetron which generates microwave energy and an inverter which converts DC voltage to high frequency AC voltage are employed. The magnetron includes a heater-cathode and an anode. The inverter includes a transformer having a gapped ferrite core, a center tapped primary winding which divides the primary into two portions, and at least a first high voltage secondary winding and a second low voltage secondary winding for the magnetron heater, and means for switching current through each winding half alternately at a periodic high frequency rate, substantially above 60 Hz., to produce a high frequency magnetic field in said ferrite core, and means, including inductor means, are provided for providing DC current into said primary winding at said center tap.

Abstract: A high-frequency heating device includes an AC power source, a high-tension transformer, a triac thyristor connected between the primary winding of the high-tension transformer and the power source, a magnetron coupled to the secondary winding of the high-tension transformer, a signal generating circuit for generating upon energization a signal at a predetermined phase of each cycle of the power source voltage, an astable multivibrator for generating pulses whose pulse width is variable, and a control circuit for generating an output signal upon receipt of both an output pulse of the astable multivibrator and output of the signal generating circuit to control the triac thyristor in an ON-OFF fashion.