Bandpass Filter Transmission Lines for Compact RF Interference Filters
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing interference mitigation filters in cellular communications systems are large, complex, and costly, with limited tunability and high sensitivity to thermal variations, particularly when implemented using the notch filter approach.
Innovation Solution
The integration of a bandpass filter as the RF transmission line within the filter housing, replacing conventional RF transmission lines, to create a more compact, cost-effective, and tunable interference mitigation filter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional RF transmission lines are used in interference mitigation filters, then the filters can pass RF signals in the passband, but the filters become large, complex, and costly
Solution Approach 1:
The patent combines the RF transmission line function with the bandpass filter function into a single integrated structure. The bandpass filter transmission lines serve dual purposes: they filter signals in the passband while simultaneously acting as the RF transmission path, eliminating the need for separate transmission line components and reducing overall filter size and complexity
Solution Approach 2:
The bandpass filter transmission lines perform multiple functions within the filter assembly. They provide signal transmission in the passband frequency range while also providing filtering functionality, effectively making the transmission line multi-functional and reducing the total component count
2Ease of manufacture
If conventional RF transmission lines are used in interference mitigation filters, then the filters can transmit RF signals, but the manufacturing cost increases
Solution Approach 1:
By merging the transmission line and bandpass filter into a single integrated component, the patent reduces the total number of parts that need to be manufactured, assembled, and tuned. This integration simplifies the manufacturing process and reduces costs while maintaining the required filtering and transmission performance through the unified bandpass filter design
3Adaptability or versatility
If notch filter approach is used to create stopband, then the filter can reject RF signals in stopband, but the filter exhibits limited tunability and high sensitivity to thermal variations
Solution Approach 1:
The patent employs bandpass filter transmission lines with adjustable resonant frequencies and coupling parameters. By changing the electrical parameters (such as capacitance, inductance, or geometric dimensions) of the bandpass filter elements, the passband and stopband frequencies can be tuned to different values, providing adaptability while the bandpass configuration inherently offers better thermal stability compared to notch filter approaches
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 solution results in filters that are smaller, less expensive, and exhibit improved performance in terms of passive intermodulation distortion and thermal stability, with enhanced tunability and the ability to be used across different passband and stopband combinations.
Implementation Method 1
a first plurality of bandpass resonators extending from the input port to the output port and configured to guide RF energy having frequencies within a passband frequency range of the filter from the input port to the output port
Implementation Method 2
a second plurality of resonant cavities disposed adjacent to the bandpass resonators, each resonant cavity having a notch resonator configured to block RF signals having frequencies within a stopband frequency range of the filter
Data Source
Figure 1A~1B
Figure 2~3A
Figure 3B~4
AI summary
Filters include a housing having an input port and an output port and a plurality of resonant cavities within the housing. Each resonant cavity may include a respective notch resonator. The filter may further include a bandpass filter that includes a plurality of bandpass resonators, the bandpass filter extending between the input port and the output port. The bandpass filter may replace a transmission line that is included in conventional filters.