Cavity Filter Coupling Sheet for Stable RF Frequency Characteristics
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Solution Overview
Problem
Cavity filters in multi-band base stations are susceptible to interference factors such as manufacturing tolerances and temperature changes, affecting their frequency characteristics and stability.
Innovation Solution
A cavity filter design incorporating a metal coupling sheet with capacitive coupling sections between resonators, allowing for self-adjustment to compensate for manufacturing and temperature-induced variations, enhancing robustness and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional cavity filters are used with fixed coupling structures, then the filter can pass signals in certain frequency ranges, but the frequency characteristics are easily affected by manufacturing tolerances and temperature changes
Solution Approach 1:
The patent applies the dynamics principle by making the coupling structure adjustable through movable coupling panels that can be positioned at different locations on the resonators. This allows the electrical coupling between resonators to be dynamically adjusted to compensate for frequency drift caused by manufacturing tolerances and temperature changes, thereby maintaining stable frequency characteristics while improving reliability
Solution Approach 2:
The patent applies the parameter changes principle by varying the position of coupling panels along the resonator surfaces to change the coupling coefficient between resonators. By adjusting the coupling parameter (coupling coefficient) rather than fixing it, the filter can adapt to different operating conditions and maintain optimal frequency characteristics despite environmental variations
2Device complexity
If the coupling between resonators is fixed, then the filter structure is simple, but the frequency characteristics may drift due to interference factors
Solution Approach 1:
The coupling structure is made dynamic by providing movable coupling panels that can be adjusted to different positions on the resonators. This allows the filter to adapt its coupling characteristics to compensate for manufacturing variations, achieving high frequency selectivity without requiring extremely tight manufacturing tolerances
Solution Approach 2:
The filter employs self-adjustment mechanisms where the coupling panels can be tuned to achieve optimal coupling coefficients. This self-service capability allows the filter to automatically compensate for manufacturing tolerances and maintain precise frequency selectivity without requiring complex external adjustment systems
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 improves the robustness and stability of the cavity filter by maintaining consistent electrical coupling despite manufacturing errors and temperature fluctuations, ensuring reliable frequency performance.
Implementation Method 1
a metal coupling sheet, which has a first coupling section positioned between the first coupling panel and the second coupling panel and a second coupling section positioned between the third coupling panel and the fourth coupling panel
Implementation Method 2
the first coupling section and the first resonator form a first capacitance and a second capacitance, and the second coupling section and the second resonator form a third capacitance and a fourth capacitance
Data Source
AI summary
A cavity filter comprises a housing which defines an internal cavity, first and second resonators in the internal cavity, and a metal coupling sheet. The first resonator has first and second spaced apart coupling panels, and the second resonator has third and fourth spaced apart coupling panels. The metal coupling sheet has a first coupling section positioned between the first coupling panel and the second coupling panel and a second coupling section positioned between the third coupling panel and the fourth coupling panel.