Folded Communication Filter With Integrated Notch Coupling
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Solution Overview
Problem
Conventional radio frequency filters face challenges in size reduction due to the extension of resonators in the thickness direction and require additional conductive components for coupling, leading to increased weight and limited usability of both sides of the printed circuit board.
Innovation Solution
A filter design using a folding method to form a cavity with notch-forming portions, including L-notch and C-notch structures, which are formed through inductive and capacitive coupling, allowing for a compact size and improved frequency characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resonators are extended in the thickness direction inside the cavity, then resonance characteristics are improved, but the filter thickness increases significantly
Solution Approach 1:
The resonators are reconfigured from a vertical extension in the thickness direction to a horizontal arrangement in the lengthwise direction. The cavity is elongated in the lengthwise direction instead of the thickness direction, allowing resonators to be disposed horizontally along the lengthwise direction. This dimensional transformation maintains resonance characteristics while significantly reducing filter thickness.
2Reliability
If additional conductive components are installed for coupling between resonators, then inductive and capacitive coupling is achieved, but the filter weight increases significantly
Solution Approach 1:
The coupling structures are integrated directly into the resonator bodies rather than being separate components. The first and second resonators each include coupling structures formed as integral parts of their respective resonator bodies, eliminating the need for additional standalone conductive components and reducing overall filter weight.
Solution Approach 2:
The resonator bodies serve multiple functions: they provide the resonant elements for frequency selection and simultaneously incorporate the coupling structures for signal transmission between resonators. This multi-functionality eliminates the need for separate coupling components.
3Length of moving object
If dielectric ceramic filter is used, then filter thickness is reduced, but both sides of the printed circuit board cannot be used
Solution Approach 1:
The filter is designed with input and output ports extending in the lengthwise direction rather than requiring thickness-direction connections. This allows the filter to be mounted on one side of the PCB while maintaining electrical connections that do not obstruct the other side of the board, enabling both sides to be utilized for other components.
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 facilitates a smaller filter thickness with enhanced frequency characteristics and usability of both sides of the main board, avoiding the need for ceramic filters and reducing weight.
Implementation Method 1
a notch-forming portion, configured to form an L-notch portion through inductive coupling
Implementation Method 2
a notch-forming portion, configured to form an L-notch portion through inductive coupling and a C-notch portion through capacitive coupling
Implementation Method 3
a resonator serves as a circuit element that resonates at a particular frequency through a combination of an inductor (L) and a capacitor (C) in an equivalent electronic circuit
Data Source
AI summary
The present disclosure relates to a filter for a communication device including: a notch-forming portion formed to extend in a predetermined direction from any one of resonant elements: a base portion, a resonant leg portion, or a resonant plate, particularly to enable multi-pass coupling, wherein at least the resonant elements are provided to be fixed to a filter housing after being manufactured from a single base material plate through press and folding processes, thereby reducing the complexity of the filter and enabling implementation of various filter functions.