Digitally Tunable Coaxial Resonator Band Reject Filter
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Solution Overview
Problem
Existing band stop filters lack the ability to be electrically tunable, relying on manual adjustments and limited resonance frequency control, which restricts their adaptability and precision in filtering specific frequency bands.
Innovation Solution
A coaxial tunable band stop filter utilizing PIN diodes and varactor diodes to electronically change the capacitance of coaxial resonators, allowing for electrical lengthening and shortening, thereby adjusting the center frequency across a bandwidth through a digital control system and inductive coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional band stop filters are used, then the filter structure is simple and easy to manufacture, but the filter cannot be electrically tuned and has limited adaptability
Solution Approach 1:
The patent applies the dynamics principle by making the filter characteristics adjustable through electrical control. Varactor diodes are used to dynamically change the capacitance values, which in turn dynamically adjust the resonance frequencies and bandwidth of the filter. This transforms a static filter into a dynamically tunable system, resolving the contradiction between simplicity and adaptability.
Solution Approach 2:
The patent employs parameter changes by varying the capacitance values of varactor diodes through applied voltages. By changing the electrical parameters (capacitance) of the tuning elements, the resonance frequency and bandwidth parameters of the filter are adjusted. This allows electrical tuning without fundamentally changing the filter structure, maintaining relative simplicity while achieving high adaptability.
2Measurement precision
If manual adjustment methods are used, then the device complexity is low, but the tuning precision and efficiency are insufficient
Solution Approach 1:
The patent replaces manual mechanical adjustment with electrical control systems. Instead of physically adjusting components by hand, voltage signals are applied to varactor diodes to electronically tune the filter. This substitution of mechanical adjustment with electrical control significantly improves tuning precision and efficiency while introducing manageable complexity through standardized electrical interfaces.
3Adaptability or versatility
If the bandwidth is fixed, then the filter design is simpler, but the filter cannot adapt to different frequency ranges
Solution Approach 1:
The patent implements universality by designing a filter structure where the same basic topology can operate across different frequency ranges and bandwidths. By using varactor diodes as universal tuning elements, the same filter circuit can be electrically reconfigured to achieve different performance characteristics, making it a multi-functional device that adapts to various applications without requiring multiple dedicated filters.
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
Enables precise and efficient tuning of the center frequency and bandwidth, enhancing the filter's adaptability and performance by allowing electronic manipulation of the resonators, improving selectivity and rejection characteristics.
Implementation Method 1
A voltage is applied to the tuning elements to change their capacitance, such that they electrically lengthen and shorten the coaxial resonator. The voltage varies the center frequency of the bandwidth.
Implementation Method 2
utilizes tuning elements, such as PIN diodes and varactor diodes, for electrically tuning a coaxial resonator to change the resonance frequency of the resonators
Implementation Method 3
The magnetic field lines of the resonator interlink with the transmission line
Data Source
AI summary
A coaxial tunable band stop filter utilizes tuning elements, such as PIN diodes and varactor diodes, for electrically tuning a coaxial resonator to change the resonance frequency of the coaxial resonators. A voltage is applied to the tuning elements to change their capacitance, such that they electrically lengthen and shorten the coaxial resonator. The variable voltages work to change the center frequency across a bandwidth. When the resonators are electrically extended or shortened in length, the center frequency in the bandwidth is changed accordingly. The bandwidth for the coaxial tunable band stop filter is tunable to increase and decrease based on the position of the center frequency. A ninety degree transmission line is used for coupling the components of the filter. A digital control is used for manipulating the tuning elements.