Waveguide EMI Filter Housing for Shielded Signal Penetration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electromagnetic interference (EMI) filters used in shielded enclosures often contribute to electromagnetic radiation, making them unintentional radiators and compromising the 'clean' environment, especially in high-speed digital signaling applications like Ethernet and PoE, where they fail to effectively reduce emissions across desired frequency ranges.
Innovation Solution
The development of EMI filters with a housing comprising conductive and non-conductive media, circuit cards for protocol conversion, and waveguides that maintain shielding effectiveness while allowing signal and power transmission, using materials like copper, silver, or gold, and dielectric media, to reduce EMI across a wide frequency range, including frequencies above 1 GHz.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional EMI filters are used in shielded enclosures, then conductors can be brought into the enclosure, but the filters contribute electromagnetic radiation and compromise the shielding integrity
Solution Approach 1:
The patent introduces waveguides as intermediary structures that allow conductors to penetrate the shielded enclosure while maintaining shielding integrity. The waveguides are designed with specific dimensional constraints (width and height less than lambda/20 at the highest operating frequency) and include irises or capacitive discontinuities that block electromagnetic radiation while permitting signal and power transmission. This intermediary structure resolves the contradiction by mediating between the need for conductor access and the requirement for EMI suppression.
2Object-affected harmful factors
If known EMI filter methods are used, then some electromagnetic interference is reduced, but the filters fail to effectively reduce emissions across the desired frequency ranges, especially above 1 GHz
Solution Approach 1:
The patent applies parameter changes by strictly controlling the waveguide dimensions (width and height) to be less than lambda/20 at the highest operating frequency, and by adjusting the iris or capacitive discontinuity parameters to achieve the desired cutoff frequency. These parameter changes enable the waveguide to effectively block electromagnetic radiation across a broad frequency range including frequencies above 1 GHz, resolving the reliability issue of conventional filters that fail at higher frequencies.
3Use of energy by moving object
If conductors penetrate the conductive material of the shielded enclosure, then power and signals can be transmitted, but the shielding ability is negated and fields pass freely
Solution Approach 1:
The patent segments the conductor penetration path into discrete waveguide structures with specific dimensional constraints. Each waveguide is designed as a separate segment with width and height less than lambda/20, and includes irises or capacitive discontinuities that segment the electromagnetic field path. This segmentation allows power and signal transmission through the conductors while preventing electromagnetic field leakage, as each segment acts as an independent barrier to radiation.
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 radiated electromagnetic emissions, maintaining shielding integrity and supporting high-speed digital protocols like 1000BASE-T and PoE, with peak emissions below 44 dBμV/m at 3 meters, enhancing the performance in both military and industrial 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 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
Implementation Method 3
at least one non-conductive based medium that transmits a signal from the first circuit card to the second circuit card
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.