Tunable Bandpass Filter Ridge Coupling Stabilization
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Solution Overview
Problem
Tunable bandpass filters face challenges in maintaining a consistent bandwidth when the center frequency of the passband is changed, leading to significant changes in the coupling coefficient, especially in high-frequency bands.
Innovation Solution
A tunable bandpass filter design incorporating a waveguide with resonators, coupling members, a ridge member, and a movable dielectric plate, where the ridge member increases the coupling coefficient between resonators and the dielectric plate's position is adjustable to change the center frequency without significantly altering the bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the center frequency of the passband is changed by adjusting the dielectric plate position, then the frequency tuning capability is improved, but the bandwidth of the passband changes significantly
Solution Approach 1:
The ridge member acts as an intermediary structure between adjacent resonators. By introducing this intermediate coupling element, the patent achieves frequency tuning through dielectric plate adjustment while the ridge member compensates for coupling coefficient variations, thereby maintaining consistent bandwidth despite frequency changes
Solution Approach 2:
The patent utilizes parameter changes in the dielectric plate position to tune the center frequency, while simultaneously employing the ridge member to counteract the resulting changes in coupling coefficient. This dual-parameter adjustment approach allows frequency tuning while maintaining bandwidth consistency
2Stability of the object's composition
If capacitive fins are arranged in the metal plate to suppress coupling coefficient changes, then the coupling stability is improved, but the device complexity increases
Solution Approach 1:
The patent extracts the coupling stabilization function from the complex capacitive fins arrangement and implements it through a simpler ridge member structure. This extracted approach achieves the same coupling coefficient stability with reduced structural complexity by using a single continuous ridge instead of multiple discrete capacitive fins
Solution Approach 2:
The ridge member can be constructed as a composite structure combining conductive materials with dielectric materials, achieving both coupling stabilization and simplified geometry. This composite approach provides the necessary electromagnetic properties while maintaining structural simplicity
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 configuration effectively suppresses changes in the bandwidth of the passband when the center frequency is adjusted, maintaining a stable coupling coefficient and desired bandwidth characteristics.
Implementation Method 1
a dielectric plate extending in the lengthwise direction of the waveguide, disposed adjacent to the plurality of resonators in a direction orthogonal to the lengthwise direction of the waveguide, and movable in the direction orthogonal to the lengthwise direction of the waveguide
Data Source
AI summary
A tunable bandpass filter (1A) includes a waveguide (11); a plurality of resonators (12) housed in the waveguide (11) and arranged in the lengthwise direction of the waveguide (11); a coupling member (13) disposed between two adjacent resonators (12); a ridge member (14) extending in the lengthwise direction of the waveguide (11) and connected to one end of the coupling member (13); and a dielectric plate (17) extending in the lengthwise direction of the waveguide (11), disposed adjacent to the plurality of resonators (12) in a direction orthogonal to the lengthwise direction of the waveguide (11), and movable in the direction orthogonal to the lengthwise direction of the waveguide (11).