Cavity Filter Layout With Integrated Notches for Thin RF Passbands
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Solution Overview
Problem
Conventional radio frequency filters face challenges in reducing size and weight due to the extension of resonators within cavities and the need for additional conductor materials for coupling, and dielectric ceramic filters restrict the use of printed circuit boards.
Innovation Solution
A filter design using a folding method to form a hexahedral cavity with notch-forming parts, including L-notch and C-notch components, which are integrated within the cavity to secure frequency characteristics while minimizing thickness and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resonators are extended within cavities in the thickness direction, then resonance frequency characteristics are achieved, but the filter size in the thickness direction increases
Solution Approach 1:
The patent transitions resonator arrangement from the thickness direction (vertical stacking) to the horizontal plane (side-by-side arrangement). Multiple resonators are positioned adjacent to each other within the same cavity layer, eliminating the need for vertical extension and reducing filter thickness while maintaining resonance frequency characteristics.
Solution Approach 2:
Multiple resonators are nested within a single cavity structure rather than requiring separate cavities for each resonator. This nesting approach allows multiple resonators to coexist in the same spatial envelope, reducing the overall filter thickness while preserving all necessary resonance characteristics.
2Reliability
If additional conductor materials are installed for inductive or capacitive coupling, then coupling characteristics are improved, but the filter weight increases
Solution Approach 1:
The patent replaces physical conductor material coupling structures with electromagnetic field-based coupling. By positioning resonators adjacent to each other within the cavity, inductive and capacitive coupling is achieved through electromagnetic field interaction rather than through additional conductor materials, significantly reducing filter weight.
Solution Approach 2:
The patent extracts and eliminates the additional conductor materials that were previously necessary for coupling. The coupling function is achieved purely through the geometric arrangement and electromagnetic interaction of the resonators themselves, removing unnecessary weight-bearing components.
3Volume of moving object
If dielectric ceramic filters are used, then compact size is achieved, but the use of both sides of PCB is restricted
Solution Approach 1:
The patent uses homogeneous conductive materials (metal layers) throughout the filter structure rather than dielectric ceramic materials. This homogeneity in material selection allows the filter to be integrated with PCB using standard conductive interconnections, enabling both sides of the PCB to be utilized while maintaining compact dimensions.
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 design allows for easy formation of notches on both sides of the passband, securing various frequency characteristics with a compact and simple structure, addressing the limitations of conventional filters.
Implementation Method 1
L-notch part through inductive coupling
Implementation Method 2
C-notch part through capacitive coupling
Implementation Method 3
a resonator is a circuit element that resonates at a specific frequency by a combination of an inductor L and a capacitor C
Data Source
AI summary
The present invention relates to a filter for a communication device, and in particular, can simplify the complexity of the filter and achieve the performance of various filters due to comprising a notch forming unit that restricts a filtering frequency area by forming prescribed notches at the left end and right end of a passband, wherein the notches are disposed closer than the separation distance between adjacent resonance elements at a portion in which magnetic field coupling between the resonance elements is dominant or a portion in which electrical field coupling between the resonance elements is dominant among at least three adjacent resonance elements sequentially selected along the longitudinal direction of a cavity for multipath coupling.