Electrical Filter With Circulator And Extracted Pole
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Solution Overview
Problem
Conventional electrical filters face challenges in achieving good input and output matches with significant amplitude variation over the passband due to resistive loss, especially at narrow bandwidths, leading to increased mid-band loss and unacceptable insertion loss, particularly at microwave frequencies.
Innovation Solution
The design incorporates a circulator with a reflection mode filter network that includes at least one resonator with a high Q factor for providing an extracted pole closest to the band edge transition frequency, allowing for reduced Q factors in other resonators without significant loss of performance, resulting in a smaller, lighter, and more cost-effective filter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional filters use multiple high Q resonators to achieve good input and output matches, then performance requirements are met, but filter size, weight, and manufacturing cost increase significantly
Solution Approach 1:
The patent applies local quality by assigning different Q factors to different resonators based on their specific functions. The first resonator (extracted pole) uses a high Q factor to provide sharp rejection at the band edge, while the second and third resonators use lower Q factors since they provide broader frequency coverage. This localized optimization of Q factors maintains overall filter performance while reducing the need for multiple high Q resonators, thereby decreasing filter size and weight.
2Object-affected harmful factors
If conventional filters use multiple high Q resonators to achieve required rejection, then stopband rejection is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent changes the Q factor parameter distribution across resonators to achieve required stopband rejection with reduced complexity. By concentrating the high Q requirement on only the first resonator (which provides the critical extracted pole for sharp band edge rejection) and using lower Q for subsequent resonators, the design meets rejection requirements while simplifying the overall device structure and reducing manufacturing complexity.
3Loss of energy
If conventional filters minimize mid-band loss, then passband transmission is improved, but amplitude variation over the passband increases
Solution Approach 1:
The patent applies local quality by optimizing each resonator's Q factor for its specific frequency range. The high Q first resonator provides sharp rejection at the band edge with minimal impact on passband, while the lower Q second and third resonators provide broader coverage that helps maintain amplitude uniformity across the passband. This localized optimization allows the system to achieve both low mid-band loss and stable amplitude composition.
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 approach enables the electrical filter to meet performance requirements with only one high Q resonator per band edge transition frequency, significantly reducing filter size, weight, and manufacturing costs while maintaining performance, and achieving the necessary rejection and passband characteristics.
Implementation Method 1
a filter network comprising at least one resonator, the filter network having a network input connected to the second circulator port; and a further resonator connected to the network input, the further resonator being arranged to provide an extracted pole providing a transmission zero closest to the band edge transition frequency
Data Source
AI summary
An electrical filter for filtering an electrical signal, the filter having a transmission characteristic comprising a band edge at a band edge transition frequency, the filter comprising a circulator having a first circulator port for receiving a signal to be filtered, the circulator being adapted to transfer a signal received at the first circulator port to a second circulator port and being further adapted to transfer a signal received at the second circulator port to a third circulator port; and, a reflection mode filter connected to the second port; the reflection mode filter comprising a filter network comprising at least one resonator, the filter network having a network input connected to the second circulator port; and, a further resonator connected to the network input, the further resonator being arranged to provide an extracted pole providing a transmission zero closest to the band edge transition frequency; wherein the further resonator has a high Q compared to the low Q of at least one of the at least one resonator of the filter network.