RF Cavity Filter Tuning Elements for Adjustable Cross-Coupling
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Solution Overview
Problem
RF cavity filters face challenges in adjusting cross-coupling amounts and transmission zeros, as existing structures cannot easily modify coupling between resonators without replacing components or altering the filter's configuration, leading to limitations in tuning the skirt characteristic and insertion loss.
Innovation Solution
The RF filter design incorporates a housing member with cavities and resonators, along with a cover that allows for the insertion of tuning elements, which are connected electrically to adjust cross-coupling amounts and transmission zeros through varying insertion depths and capacitance control using lumped elements or sliding members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the coupling bar size is fixed to determine coupling amount, then the structure is simple, but the coupling amount cannot be adjusted without replacing components
Solution Approach 1:
The coupling bar is designed with a movable portion that can slide along the wall between cavities, transforming the fixed coupling structure into an adjustable one. The movable portion changes position to modify coupling amount between resonators, enabling dynamic adjustment without component replacement.
Solution Approach 2:
The movable portion is nested within the coupling bar structure, allowing it to slide along the wall while remaining part of the overall coupling mechanism. This nested design enables adjustment functionality without adding external components.
2Manufacturing precision
If the number of cavities and resonators is increased to improve skirt characteristic, then the skirt characteristic is enhanced, but the insertion loss increases
Solution Approach 1:
The invention adjusts the coupling amount between specific resonators using the movable portion of the coupling bar to create transmission zeros. By changing the coupling parameter, the skirt characteristic is sharpened without requiring additional cavities or resonators, thus avoiding increased insertion loss.
Solution Approach 2:
The movable portion acts as an intermediary element that enables cross-coupling between non-adjacent resonators. This cross-coupling creates transmission zeros that improve the skirt characteristic without adding more resonators to the filter structure.
3Ease of operation
If the coupling bar is set on the wall with fixed position, then the structure is stable, but the coupling amount cannot be adjusted under operating conditions
Solution Approach 1:
The coupling bar incorporates a movable portion that can slide to different positions along the wall, enabling adjustment of coupling amount while maintaining structural integrity. The movable portion is constrained to move only in the desired direction while remaining securely attached to the wall.
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 enables wide-range adjustment of coupling coefficients and transmission zeros, allowing for improved tuning of the filter's characteristics without increasing insertion loss, facilitating easier user control over the filter's performance.
Implementation Method 1
capacitance control using lumped elements or sliding members
Implementation Method 2
Each of the cavities 110, 112, 114, 116, 118 and 120 and corresponding resonators 130, 132, 134, 136, 138 and 140 function as LC resonance elements
Data Source
AI summary
An RF filter, e.g. RF cavity filter for adjusting coupling amount or transmission zero is disclosed. The RF filter includes a housing member in which cavities are defined by walls, resonators located in the cavities, a cover combined with an upper surface of the housing member, a first tuning element inserted into a first cavity of the cavities through the cover, and a second tuning element inserted into a second cavity of the cavities through the cover. Here, the first tuning element and the second tuning element are connected electrically.