Optical EMI Filter Housing for Shielded Signal Transmission
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Solution Overview
Problem
Existing electromagnetic interference (EMI) filters used in shielded enclosures often contribute to electromagnetic interference themselves, acting as unintentional radiators and compromising the 'clean' environment they are intended to protect, especially in high-frequency data transmission applications.
Innovation Solution
The development of EMI filters with a housing comprising conductive and non-conductive media, circuit cards that convert signals between these media, and waveguides that minimize EMI through specific aperture designs, ensuring shielding effectiveness while allowing signal transmission, including Power over Ethernet (PoE) and compliance with high-speed protocols like IEEE 802.3 and 1000BASE-T.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional EMI filters are used to allow conductors into shielded enclosures, then signal transmission is enabled, but the filters act as unintentional radiators and compromise the shielding integrity
Solution Approach 1:
The patent introduces an optical intermediary (optical fiber) between the external environment and the shielded enclosure. Data signals are converted from electrical to optical form, transmitted through the optical fiber which does not radiate electromagnetic energy, and then converted back to electrical signals inside the enclosure. This intermediary approach allows signal transmission while eliminating the filter's role as an unintentional radiator.
Solution Approach 2:
The patent replaces the traditional electrical/conductive signal transmission mechanism with an optical transmission mechanism. Instead of using conductive cables that require EMI filtering, the system uses optical fibers that transmit data as light pulses, fundamentally substituting the transmission medium to eliminate electromagnetic radiation issues.
2Ease of operation
If conductive materials are used to penetrate shielded enclosures for power or signals, then electrical connectivity is achieved, but the shielding effectiveness is negated and fields pass freely
Solution Approach 1:
The patent uses optical fiber as an intermediary medium that passes through the shielded enclosure without compromising its integrity. The optical fiber acts as a non-conductive bridge that allows data transmission while maintaining the electromagnetic shield, as light transmission does not create electromagnetic fields that would penetrate or leak through the shielding.
Solution Approach 2:
The patent employs optical fiber, which can be considered a flexible transmission medium that passes through the shielded enclosure. The optical fiber's flexible nature allows it to be routed through the enclosure while its non-conductive properties ensure it does not compromise the shielding effectiveness, unlike rigid conductive materials.
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
These filters significantly reduce EMI in shielded environments, maintaining shielding integrity and reducing radiated electromagnetic emissions to levels compliant with stringent standards, such as MIL-STD-810 and FCC Part 15, across a wide frequency range, even in ruggedized applications.
Implementation Method 1
at least one waveguide through which the non-conductive based medium passes from the first compartment to the second compartment
Implementation Method 2
a first circuit card located in the first compartment of the housing that converts a signal transmitted on a conductive based medium to a signal transmitted on a non-conductive based medium
Implementation Method 3
a second circuit card located in the second compartment of the housing that converts a signal transmitted on a non-conductive based medium to a signal transmitted on a conductive based medium
Implementation Method 4
A shielded enclosure blocks out an external electromagnetic field because the electrical charges within the enclosure's conductive material redistribute themselves until the external field's effects are cancelled
Data Source
AI summary
Provided herein are methods, devices, and systems that relate to electromagnetic interference (EMI) filters that, in certain embodiments, comprise: (a) a housing comprising a substantially enclosed first compartment and a substantially enclosed second compartment; (b) a first circuit card located in the first compartment of the housing that converts a signal transmitted on a conductive based medium to a signal transmitted on a non-conductive based medium; (c) a second circuit card located in the second compartment of the housing that converts a signal transmitted on a non-conductive based medium to a signal transmitted on a conductive based medium; (d) at least one non-conductive based medium that transmits a signal from the first circuit card to the second circuit card; and (e) at least one waveguide through which the non-conductive based medium passes from the first compartment to the second compartment.