Magnetic Field Mitigation of Passive Intermodulation Distortion
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Solution Overview
Problem
Passive intermodulation distortion in communications and sensing systems, particularly in coaxial connectors and other RF components, is a significant issue due to the nonlinearity of ferromagnetic materials, leading to interference and saturation of receive signals, which conventional methods like frequency filtering cannot effectively mitigate.
Innovation Solution
A strong external static magnetic field is applied to reduce the intermodulation distortion in components containing ferromagnetic materials like nickel or steel, by lowering the series resistance and inductance through the magneto-impedance effect, thereby linearizing the magnetic permeability and diminishing the nonlinear behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If ferromagnetic materials (nickel, steel) are used in RF components, then mechanical strength and durability are improved, but passive intermodulation distortion increases due to nonlinear magnetic permeability
Solution Approach 1:
The patent applies an external static magnetic field to change the magnetic state of ferromagnetic materials, transforming them from a nonlinear hysteretic state to a linearized saturated state. This parameter change in magnetic permeability reduces PIM distortion while preserving the mechanical strength benefits of ferromagnetic materials in RF components
Solution Approach 2:
The patent introduces an external magnetic field as an intermediary agent that mediates between the conflicting requirements of mechanical strength and low PIM. The magnetic field acts on the ferromagnetic material to linearize its permeability, enabling the material to maintain strength while reducing distortion
2Object-generated harmful factors
If magnetic field is applied to reduce PIM, then intermodulation distortion is reduced by up to 40 dB, but additional system complexity is introduced
Solution Approach 1:
The patent applies the magnetic field in advance to pre-linearize the magnetic permeability of ferromagnetic materials before RF signals are processed. This preliminary action ensures that the materials operate in a linear regime throughout signal transmission, maintaining low PIM without requiring complex real-time control systems
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 application of a magnetic field results in a significant reduction of passive intermodulation distortion by up to 40 dB, making it effective for both mitigation and localization of distortion sources without affecting the geometries of shielded structures, and is applicable to various RF components including coaxial connectors and antennas.
Implementation Method 1
the nonlinear behavior is believed to be caused by the hysteretic relationship between the magnetization of the ferromagnetic material and any imposed magnetic field
Implementation Method 2
lowering the series resistance and inductance through the magneto-impedance effect
Data Source
AI summary
A magnetic field method for mitigating passive intermodulation distortion. The method is useful both for mitigating passive intermodulation and for easily locating dominant sources of it, even in shielded components.