Micro-strip Band Pass Filter with Resonating Cavities
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Solution Overview
Problem
Existing band pass filters in superheterodyne receivers face challenges in effectively rejecting image frequency interference, which affects signal quality and efficiency, and increasing the order of resonators to improve rejection leads to larger circuit size and higher costs.
Innovation Solution
A band pass filter design that includes resonating cavities formed in micro-strip ports between the input and output ports, allowing for enhanced image frequency rejection without increasing the number of resonators, thereby maintaining circuit area and improving signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the order of resonators in the band pass filter is increased to improve image frequency rejection, then the image frequency rejection ratio is improved, but the circuit area increases and manufacturing cost increases
Solution Approach 1:
The patent changes the structural parameters of the micro-strip ports by forming resonating cavities within them. This modifies the electrical characteristics of the filter without adding more resonators, thereby achieving improved image frequency rejection while maintaining the same circuit area. The resonating cavities create additional resonance effects that enhance the filtering performance at image frequencies.
2Reliability
If the order of resonators in the band pass filter is increased to improve image frequency rejection, then the image frequency rejection ratio is improved, but the manufacturing cost increases
Solution Approach 1:
The patent modifies the structure of existing micro-strip ports by forming resonating cavities, which can be achieved through standard PCB fabrication processes like etching. This approach avoids the need to manufacture additional resonator components, thereby reducing manufacturing complexity and cost while achieving the desired improvement in image frequency rejection ratio.
3Reliability
If resonating cavities are formed in micro-strip ports, then image frequency rejection is enhanced without increasing circuit area, but the structural complexity of the filter increases
Solution Approach 1:
The patent makes the micro-strip ports serve multiple functions: they continue to provide signal transmission paths while also functioning as resonating structures that reject image frequencies. By forming resonating cavities within the ports, the same structural element performs both coupling and filtering functions, thereby enhancing image rejection without adding separate components or increasing overall structural complexity.
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 proposed design achieves a significant increase in image frequency rejection ratio, meeting standards while reducing circuit size and cost, thereby enhancing signal receiving efficiency.
Implementation Method 1
a plurality of resonators arranged between the first micro-strip port and the second micro-strip port for performing band pass filtering on the radio-frequency signal
Implementation Method 2
at least one resonating cavity formed in each of the first micro-strip port and the second micro-strip port for enhancing rejecting effect of image frequency
Data Source
AI summary
A band pass filter includes a first micro-strip port for receiving a radio-frequency signal, a second micro-strip port for outputting a filtered radio-frequency signal and comprising at least one resonating cavity formed for enhancing rejecting effect of image frequency corresponding to the filtered radio-frequency signal, and a plurality of resonators arranged between the first micro-strip port and the second micro-strip port for performing band pass filtering on the radio-frequency signal to generate the filtered radio-frequency signal.