Dielectric Waveguide Filter Alternating Coupling
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Solution Overview
Problem
Dielectric waveguide filters with conventional inductive coupling exhibit gentle attenuation characteristics from the pass band to a higher band, requiring an increased number of resonator stages, leading to insertion loss, while capacitive coupling causes spurious responses in the lower band.
Innovation Solution
A dielectric waveguide filter design incorporating alternately arranged inductive and capacitive coupling portions along the main coupling path, with capacitive coupling portions interposed between inductive coupling portions to prevent spurious responses and achieve steep attenuation characteristics with fewer resonator stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If only inductive coupling is used in the main coupling path, then the structure is simple, but the attenuation characteristics from pass band to higher band become gentle
Solution Approach 1:
The patent combines inductive coupling portions and capacitive coupling portions in an alternating arrangement along the main coupling path. This merging of two different coupling mechanisms achieves steep attenuation characteristics from the pass band to the higher band while maintaining a manageable structure that does not require excessive numbers of resonator stages.
2Reliability
If only capacitive coupling is used in the main coupling path, then steep attenuation characteristics are achieved, but spurious responses occur in the lower band
Solution Approach 1:
The patent applies different coupling types at different locations along the main coupling path. Inductive coupling portions and capacitive coupling portions are alternately arranged, so that each portion contributes its advantageous local characteristics: capacitive portions provide steep attenuation while inductive portions suppress spurious responses in the lower band.
3Reliability
If the number of resonator stages is increased to achieve steep attenuation characteristics, then the attenuation performance improves, but the insertion loss in the pass band increases
Solution Approach 1:
The patent changes the coupling mechanism parameter by introducing capacitive coupling portions with specific capacitance values (e.g., 0.2-2.0 pF) to achieve steep attenuation characteristics. This allows the filter to attain the desired attenuation performance with a reduced number of resonator stages, thereby reducing insertion loss in the pass band.
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 filter achieves steep attenuation characteristics from the pass band to a higher band with a reduced number of resonator stages and minimizes spurious responses in the lower band, enhancing performance by combining inductive and capacitive coupling effectively.
Implementation Method 1
Inductive coupling has been conventionally used for coupling of resonators that forms the main coupling path
Implementation Method 2
The main coupling path may be composed of capacitive coupling
Implementation Method 3
a plurality of dielectric waveguide resonators arranged along a main coupling path for signal propagation
Data Source
AI summary
A dielectric waveguide filter includes at least four dielectric waveguide resonators arranged along a main coupling path for signal propagation, and main coupling portions each of which is provided between the dielectric waveguide resonators that are adjacent to each other along the main coupling path among the at least four dielectric waveguide resonators. The main coupling portions include an inductive coupling portion and a capacitive coupling portion, and the inductive coupling portion and the capacitive coupling portion are alternately and repeatedly arranged along the main coupling path.