Magnetron Filter Board RF Band-Gap Noise Mitigation
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Solution Overview
Problem
Microwave ovens operating in aircraft galleys or airworthy environments face challenges with electromagnetic noise emissions due to the connection between magnetrons and power supply units, which interfere with other aircraft systems operating in the same frequency ranges.
Innovation Solution
A magnetron filter board incorporating a printed circuit board with RF band-gap filters, configured as a π topology, is used to mitigate noise by connecting between the magnetron and the power supply unit, utilizing high-voltage and high-current capable traces to attenuate electromagnetic noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional cable connections are used between magnetron and power supply unit, then the system structure is simple, but electromagnetic noise is radiated throughout the system
Solution Approach 1:
The patent extracts the harmful electromagnetic radiation function from the cable connection by removing the cable entirely and replacing it with a printed circuit board trace connection. The magnetron is directly mounted on the filter board with electrical connections made through PCB traces rather than external cables, thereby eliminating the antenna effect that causes EM radiation while maintaining the power supply function.
Solution Approach 2:
The printed circuit board serves as an intermediary between the magnetron and power supply unit, providing both electrical connection and electromagnetic filtering functions. The PCB traces are designed with specific impedance and routing to act as a controlled transmission medium that prevents EM radiation while maintaining signal integrity and power delivery.
2Object-affected harmful factors
If filters with extra components like coils or capacitors are added, then electromagnetic noise is reduced, but device complexity and potential reliability issues increase
Solution Approach 1:
The patent merges the filtering function with the existing PCB trace structure rather than adding separate filter components. The ground traces and power traces are configured to work together as an integrated filtering system, where the PCB layout itself provides the noise mitigation function without requiring additional coils, capacitors, or other discrete filter components.
Solution Approach 2:
The printed circuit board structure serves itself by using its own trace geometry and grounding configuration to provide electromagnetic filtering. The ground traces are positioned and dimensioned to create capacitive coupling that shunts noise to ground, while the power traces are routed to minimize radiation, allowing the PCB to filter noise inherent in its own structure without external assistance.
3Adaptability or versatility
If cable connections are used between magnetron and power supply unit, then installation is simple, but electromagnetic interference with aircraft systems occurs
Solution Approach 1:
The patent changes the electrical parameters of the connection by transitioning from high-inductance cable connections to low-inductance PCB trace connections. The trace geometry, width, and routing are optimized to control impedance and minimize electromagnetic radiation, thereby changing the electrical characteristics to meet aircraft emission standards while maintaining functional connectivity.
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
The solution effectively reduces electromagnetic noise emissions by at least 20 dB, ensuring compliance with stringent electromagnetic emission requirements in aircraft environments without adding extra components like coils or capacitors, thus maintaining reliability.
Implementation Method 1
The first trace and the second trace can be configured as a radio frequency band-gap filter that mitigates noise associated with the connection between the magnetron and the power supply unit
Implementation Method 2
Microwave ovens generate power via magnetrons, or magnetron tubes (MGT) coupled to a high voltage power supply unit (PSU). Whenever a magnetron generates radiated power, however, the cables connecting the PSU to the magnetron's leads may radiate electromagnetic (EM) noise throughout the entire system.
Data Source
AI summary
A magnetron filter board for a microwave oven is disclosed. In embodiments, the magnetron filter board includes a printed circuit board with a first trace and a second trace on the printed circuit board. The first trace includes a first end for connecting to a magnetron and a second end for connecting to a power supply unit. The second trace also includes a first end for connecting to the magnetron and a second end for connecting to the power supply unit. The first trace and the second trace can be configured as a radio frequency band-gap filter that mitigates noise associated with the connection between the magnetron and the power supply unit.