Folded Single-Plate RF Filter for Low-Loss Slim PCB Integration
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Solution Overview
Problem
Conventional radio frequency filters face challenges in reducing thickness and weight due to the need for additional conductor materials for inductive or capacitive coupling, and dielectric ceramic filters are limited by their attachment to one surface of a printed circuit board, hindering slimness and reliability.
Innovation Solution
A filter for communication devices using a single base material plate that forms a cavity through folding, minimizing bonding processes and incorporating a conductive sheet material with a thickness of 3 t or less, and includes a resonator panel and tuning bars to reduce insertion loss and enhance coupling stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional conductor materials are installed for inductive or capacitive coupling in conventional radio frequency filters, then coupling between resonators is improved, but weight of the filter is greatly increased
Solution Approach 1:
The patent removes the additional conductor materials from the filter structure and instead uses the ground plane of the PCB as the coupling element. This extraction of unnecessary components directly reduces filter weight while maintaining coupling functionality through the PCB's inherent ground structure.
Solution Approach 2:
The ground plane, which is already present as part of the PCB structure, is utilized for dual purposes: providing electrical grounding and enabling inductive or capacitive coupling between resonators. This multi-functional use eliminates the need for separate coupling conductors, reducing weight while maintaining coupling characteristics.
2Ease of manufacture
If dielectric ceramic filter is directly attached to one surface of main board, then manufacturing is simplified, but both surfaces of PCB cannot be used and slimness is hindered
Solution Approach 1:
The filter structure is transitioned from a surface-mounted configuration to a through-hole configuration that penetrates the PCB thickness dimension. By forming cavities through the PCB and placing resonators within these through-holes, the design utilizes the third dimension (thickness) of the PCB, enabling both top and bottom surfaces to remain available for other components while maintaining manufacturing simplicity.
3Strength
If conventional bonding process is used for forming cavity and preparing resonator structure, then structural integrity is ensured, but insertion loss increases
Solution Approach 1:
The cavity formation process is merged with the PCB manufacturing process itself. Instead of separate bonding steps to attach resonators and form cavities, the resonators are directly integrated into cavities formed within the PCB structure during the same manufacturing sequence, eliminating bonding interfaces and associated insertion losses while maintaining structural integrity.
Solution Approach 2:
The PCB material itself serves as the intermediary that provides both the structural support for the cavity and the mounting medium for the resonators. This eliminates the need for separate bonding materials and processes, reducing insertion loss while ensuring structural integrity through the PCB's inherent mechanical properties.
4Length of moving object
If base material plate thickness is reduced for slim design, then product slimness is achieved, but coupling stiffness of thin plate is insufficient
Solution Approach 1:
The thin base material plate is segmented into multiple folded sections that form the cavity structure. By folding the plate rather than using a single flat sheet, the design achieves the necessary three-dimensional cavity volume and structural rigidity while maintaining a thin overall profile, thus preserving coupling stiffness despite reduced material thickness.
Solution Approach 2:
The flat base material plate is transformed through folding into a three-dimensional curved or angular cavity structure. This curvature and three-dimensional configuration provide structural stiffness and mechanical strength that would be absent in a flat thin plate, enabling adequate coupling stiffness while maintaining slimness through the use of thin material.
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 solution reduces insertion loss and improves communication reliability while achieving a lightweight and slim design by utilizing a thin base material plate and folding process, enhancing the coupling stiffness and reducing the thickness of antenna devices.
Implementation Method 1
a resonator is a circuit element that resonates in a specific frequency by a combination of an inductor L and a capacitor C in an equivalent electronic-circuit way. Each resonator has a structure in which a dielectric resonance (DR) element or a metal resonance element is installed within a metallic cylinder or a cavity
Implementation Method 2
the installation of an additional component of a conductor material in order to implement inductive coupling or capacitive coupling so as to enhance a skirt characteristic between adjacent resonators
Implementation Method 3
the installation of an additional component of a conductor material in order to implement inductive coupling or capacitive coupling
Data Source
AI summary
The present invention relates to a filter for a communication device and a manufacturing method therefor, and, particularly, the filter comprises a single base plate, which is provided as a conductive board with a predetermined thickness or less that forms an inner side surface of a cavity for performing frequency filtering, wherein the cavity is formed by folding at least a portion of the base plate, and thus manufacturing is facilitated and overall slimming and lightening of a product can be sought.