Band Stop Filter With Stepped Cavity Suppressing Parasitic Resonance
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Solution Overview
Problem
Existing radio frequency filters using resonators face challenges in effectively restraining parasitic resonance modes, achieving a smaller size, and easily tuning filtering characteristics.
Innovation Solution
A band stop filter design featuring a multi-stage cavity structure with a narrower upper end portion, a resonant bar mounted to a lower cover, a transmission line within a groove, and an airtight cover, which increases capacitance and reduces inductance to suppress parasitic resonance modes and allow for size reduction and tuning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional resonant circuit with coil and condenser is used, then the circuit can resonate radio frequency, but it produces high radiation loss and is not suitable for super high frequency
Solution Approach 1:
The patent replaces the conventional mechanical resonant circuit (coil and condenser) with a dielectric resonator system. The dielectric resonator uses electromagnetic resonance in a dielectric material instead of mechanical oscillation, eliminating radiation loss while maintaining resonance capability at super high frequencies.
Solution Approach 2:
The patent changes the resonance mechanism by using a dielectric material with specific permittivity instead of conductive elements. This parameter change allows the system to achieve resonance at super high frequencies with minimal radiation loss, as the dielectric confines the electromagnetic field more effectively.
2Reliability
If the cavity width is increased to improve resonance characteristics, then the filtering characteristic improves, but the filter size increases
Solution Approach 1:
The patent optimizes the cavity dimensions by changing the width parameter to create a multi-stage structure. The first cavity has a different width than the second cavity, allowing each to be tuned for optimal resonance characteristics while maintaining a compact overall size. This dimensional parameter optimization achieves good filtering performance without excessive size increase.
Solution Approach 2:
The patent divides the resonant system into multiple separate cavities (first cavity and second cavity) instead of using a single large cavity. Each cavity can be independently optimized for size and resonance characteristics, allowing the overall filter to achieve good performance while maintaining a compact form factor through modular segmentation.
3Ease of manufacture
If the cavity structure is simplified for easier manufacture, then manufacturing becomes easier, but the ability to restrain parasitic resonance modes deteriorates
Solution Approach 1:
The patent uses multiple separate cavities instead of a single complex cavity structure. This segmentation simplifies manufacturing as each cavity can be fabricated independently using standard techniques, while the multi-cavity arrangement inherently suppresses parasitic resonance modes by providing isolated resonance paths.
Solution Approach 2:
The patent introduces a dielectric member as an intermediary element between the cavities and resonators. This dielectric member helps control and restrain parasitic resonance modes by modifying the electromagnetic field distribution, while not complicating the overall cavity structure or manufacturing process.
4Volume of moving object
If the resonator structure is optimized for size reduction, then the filter becomes more compact, but the tuning capability of filtering characteristic becomes more difficult
Solution Approach 1:
The patent divides the system into multiple cavities and resonators that can be independently adjusted. This segmentation allows tuning to be performed on individual components rather than the entire system, making it easier to achieve desired filtering characteristics in a compact configuration.
Solution Approach 2:
The patent incorporates adjustable elements within the compact cavity structure, allowing the resonant frequency and filtering characteristics to be tuned dynamically. This enables easy adjustment of filtering parameters while maintaining a reduced overall filter size through efficient space utilization.
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 effectively suppresses parasitic resonance modes, provides a wideband pass band, and enables easy tuning of filtering characteristics while minimizing the filter's size.
Implementation Method 1
each resonator forms a metal cylindrical or rectangular cavity surrounded by a conductor. The resonator has a Dielectric Resonance (DR) element or a resonance element including a metal resonant bar within the resonator, and allows only an electromagnetic field of a natural frequency to exist therein, so that the resonator has a structure enabling a resonance of a super high frequency.
Implementation Method 2
designing the cavity to have a multi-stage structure in such a manner that a width of at least a part of an upper end portion of the cavity is narrower than that of a lower end portion of the cavity
Implementation Method 3
increases capacitance and reduces inductance to suppress parasitic resonance modes
Implementation Method 4
a transmission line installed within a groove preset to the housing such that the transmission line is coupled to a resonator formed by the cavity and the resonant bar within the cavity, and connected between a signal input terminal and a signal output terminal
Data Source
AI summary
The present invention relates to a band stop filter comprising: a resonating bar; a housing on the inside of which is formed a receiving space where the resonating bar is positioned, and which is made in a stepped form such that at least one part of an upper-end part is narrower than a lower-end part in terms of the internal width of the receiving space during the formation of the receiving space; a lower cover which has the resonating bar fitted thereto, is joined to the lower part of the housing and, when so joined, is assembled such that the resonating bar is inserted into the receiving space, and which forms the floor surface of the receiving space; and a hermetic-sealing cover which is provided within a recess pre-made in the housing in such a way as to couple with a resonator formed by the receiving space and the resonating bar on the inside of the receiving space, and is designed to hermetically seal the recess in the housing where a transmission line has been provided.