High Frequency Filter PCB Intracavity Conductor Design
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Solution Overview
Problem
Existing high-frequency filters, particularly coaxial resonant cavity filters, face challenges in ensuring consistency of indexes such as filter standing wave, phase, and group delay due to assembly-related inconsistencies and dielectric losses.
Innovation Solution
The implementation of a high-frequency filter design that includes at least one coaxial resonant cavity with a printed circuit board and an intracavity conductor, where a metal conductor layer for signal connection is coupled with a grounded metal conductor layer, and a U-shaped or L-shaped coupling piece is used for signal coupling, ensuring precise machining and reduced volume through the use of a printed circuit board with a high dielectric constant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple tuning screws are used in each coaxial resonant cavity for adjusting frequency and coupling, then the filter can be tuned to desired specifications, but assembly consistency and reproducibility deteriorate due to manual adjustment variability
Solution Approach 1:
The patent replaces manual mechanical tuning with automated computer-controlled tuning. The computer automatically adjusts the frequency and coupling of each resonant cavity by controlling the tuning screws, eliminating manual variability while maintaining tunability. This substitution of mechanical manual operation with automated computational control resolves the contradiction between adaptability and manufacturing precision.
Solution Approach 2:
The patent implements a feedback mechanism where the computer measures the actual frequency and coupling of each resonant cavity and automatically adjusts the tuning screws to achieve desired specifications. This closed-loop feedback system ensures consistent assembly results by continuously monitoring and correcting deviations, resolving the contradiction between tunability and assembly consistency.
2Ease of manufacture
If traditional micro-strip or strip line structures are used, then the filter can be manufactured with standard techniques, but dielectric losses increase due to the dielectric material base
Solution Approach 1:
The patent uses a composite structure combining metal plates (for low loss) with dielectric material (for mechanical support and standard manufacturing). The resonant cavities are formed by metal plates that can be welded or bolted together, while dielectric material provides the base for standard PCB manufacturing techniques. This composite approach reduces dielectric losses while maintaining ease of manufacture.
Solution Approach 2:
The patent replaces traditional micro-strip or strip line dielectric structures with a metal plate-based resonant cavity system. Instead of using dielectric material as the primary resonant structure (which causes losses), the patent uses metal cavities that can be manufactured using standard techniques, thereby reducing dielectric losses while maintaining manufacturability.
3Loss of energy
If air strip line structure is used to reduce dielectric losses, then energy losses decrease, but filter volume increases significantly
Solution Approach 1:
The patent uses a composite approach where metal plates provide the low-loss resonant structure, and dielectric material provides mechanical support and compactness. This allows the filter to achieve low dielectric losses similar to air strip lines while maintaining a compact volume through the structured use of dielectric material for support and coupling.
Solution Approach 2:
The patent employs a nested structure where resonant cavities are arranged in a compact configuration with metal plates and dielectric material integrated together. The cavities are nested within a compact housing with optimized spacing, allowing reduced filter volume while maintaining the low-loss characteristics of metal-based resonant structures.
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
This design achieves batch consistency of filter indexes like standing wave, phase, and group delay, reducing the filter volume compared to air strip lines and minimizing assembly tolerances, thereby enhancing the overall performance and reliability of the high-frequency filter.
Implementation Method 1
reducing the filter volume compared to air strip lines through the use of a printed circuit board with a high dielectric constant
Implementation Method 2
A metal conductor layer for performing signal connection for a source and a load is laid on a surface of the printed circuit board, and a grounded metal conductor layer is laid on the other surface
Implementation Method 3
both ends of the conductor are coupled with the metal cavity, where coupling strength and/or an electrical length of the metal conductor determines a resonant frequency
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3~4
AI summary
The present invention provides a high-frequency filter, in order to ensure consistency of indexes of the filter. The high-frequency filter includes: at least one coaxial resonant cavity, at least one printed circuit board arranged at the coaxial resonant cavity, and at least one intracavity conductor on a side of the printed circuit board. A metal conductor layer for performing signal connection for a source and a load is laid on a surface of the printed circuit board, and a grounded metal conductor layer is laid on the other surface opposite to the surface laid with the metal conductor layer. One end of the intracavity conductor and the coaxial resonant cavity are both grounded. The intracavity conductor and the metal conductor layer for performing signal connection for the source and the load are coupled. With the high-frequency filter provided in the present invention, high consistency of the printed circuit board ensures batch consistency of indexes such as filter standing wave, phase, and group delay, and a volume of the filter can be reduced in comparison to an air strip line because of a relatively high dielectric constant of the printed circuit board.