Short RF Pulse Generation Using Stacked Magnetron Drive
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Solution Overview
Problem
Conventional methods are unable to generate high-powered microwaves with very short durations, such as 40-100 nanoseconds, using low frequency magnetrons due to the incompatibility of rapidly rising pulses with the slower rise time requirements of these magnetrons, leading to potential misfiring and arc-over issues.
Innovation Solution
A system comprising a first circuit generating a high voltage pedestal pulse and a second circuit generating a high voltage short pulse, which are combined to create a stacked pulse, allowing the low frequency magnetron to oscillate before generating a short RF pulse, utilizing a Darlington Network and resonant charging components to control and adjust the pulse voltages, ensuring proper oscillation and minimizing power supply size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a rapidly rising pulse is applied to a low frequency magnetron to achieve short pulse duration, then the pulse duration is reduced, but misfiring and arc-over occur due to the slower rise time requirements of the magnetron
Solution Approach 1:
The pulse forming network is divided into multiple discrete stages (firstPFN, secondPFN, thirdPFN, fourthPFN) that sequentially shape the voltage pulse. Each stage contributes to building the complex pulse waveform with the required slow initial rise followed by sharp transition, allowing independent optimization of each segment's function.
Solution Approach 2:
The firstPFN generates a preliminary voltage pulse with a slow rise time that prepares the magnetron for oscillation without causing misfiring. This preliminary action establishes the correct operating mode before the main high-voltage pulse arrives, ensuring reliable magnetron operation followed by the short RF pulse generation.
2Reliability
If a slowly rising modulator pulse is used to properly initiate oscillation in a low frequency magnetron, then reliable oscillation is achieved, but the pulse duration becomes excessively long
Solution Approach 1:
The pulse forming network dynamically transitions from a slow rise time phase to a fast rise time phase. The circuit parameters are designed to automatically change the pulse characteristics during operation: initially providing a slow rise for reliable oscillation initiation, then transitioning to a rapid voltage increase that terminates the pulse after a precise short duration.
Solution Approach 2:
The circuit parameters (capacitance values, inductance values, resistance values) are specifically selected to transform the pulse waveform characteristics. The firstPFN uses C1, L1, R1 to create the slow initial rise, while subsequent stages use different parameter combinations to achieve the sharp transition and controlled pulse width, changing the electrical parameters throughout the pulse formation process.
3Duration of action of moving object
If conventional pulse compression systems are used to achieve high range resolution with short pulses, then short pulse capability is obtained, but system complexity and cost increase
Solution Approach 1:
The pulse forming network serves multiple functions within a single integrated system: it generates the magnetron drive pulse, shapes the RF output pulse duration, provides impedance matching, and controls the pulse timing characteristics. This multi-functionality eliminates the need for separate pulse compression equipment, achieving short pulse operation with a standard low frequency magnetron.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables the generation of high-powered microwaves with durations less than 130 nanoseconds, effectively testing electronic components for susceptibility to microwave interference while maintaining a compact, lightweight, and cost-effective system design.
Implementation Method 1
wait for the voltage of the combined high voltage pulse to exceed a Hartree voltage of the low frequency magnetron, thereby causing the low frequency magnetron to oscillate and generate a high frequency wave
Implementation Method 2
a resonant charging component, located between the respective power supply and a respective Darlington Network or modulator
Data Source
AI summary
A system and method for generating a plurality of short RF pulses. The system and method comprises a first circuit comprising a first power supply and a plurality of first networks for generating a first output signal in a form of a high voltage pedestal pulse supplied to a common node, and a second circuit comprising a second power supply and a plurality of second networks for generating a second output signal in a form of a high voltage short pulse which is supplied to the common node. The pedestal pulse passes through a blocking inductor before being combined with the short pulse at the common node, and the short pulse is stacked on top of the pedestal pulse to form a combined high voltage pulse. A low frequency magnetron is coupled to the common node for receiving the stacked combined high voltage pulse and generating a short RF pulse.