Grounded Half-Wave RF Filter Layout for Lower Insertion Loss
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Solution Overview
Problem
Existing distributed element RF filters, particularly quarter-wave resonators, suffer from high insertion loss and inadequate stopband rejection, deviating from desired low-loss passbands.
Innovation Solution
Implementing fully grounded half-wave resonators with direct electrical connections to a ground plane, utilizing symmetrical resonator configurations and dielectric gaps to reduce reflections, and optionally incorporating a conductive cover to enhance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If quarter-wave resonators are used in distributed element RF filters, then the filter structure is simpler and easier to manufacture, but insertion loss increases and stopband rejection deteriorates
Solution Approach 1:
The patent changes the resonator electrical length parameter from quarter-wave to half-wave, and modifies the grounding configuration from partial to full grounding. This parameter change transforms the resonator's electrical characteristics, reducing insertion loss while maintaining manufacturing feasibility through standard PCB fabrication processes.
Solution Approach 2:
The patent adds the grounding dimension to the resonator structure by implementing full grounding at both ends of half-wave resonators, in addition to the dimensional changes in resonator length. This multi-dimensional modification optimizes both insertion loss and stopband rejection while keeping the planar PCB structure intact.
2Device complexity
If quarter-wave resonators are used in distributed element RF filters, then the filter structure is simpler, but stopband rejection becomes inadequate
Solution Approach 1:
The patent modifies the resonator electrical length parameter from quarter-wave to half-wave, which fundamentally changes the resonator's frequency response characteristics. This parameter change enhances stopband rejection by creating deeper nulls at stopband frequencies while maintaining a relatively simple filter structure.
Solution Approach 2:
The patent adds the grounding dimension by implementing full grounding at both ends of resonators, transforming the boundary conditions. This dimensional addition to the resonator configuration improves stopband rejection by creating more effective electromagnetic isolation without significantly increasing device complexity.
3Device complexity
If quarter-wave resonators are used, then the filter design is simpler, but passband flatness and low-loss performance deviate from desired characteristics
Solution Approach 1:
The patent changes the resonator electrical length parameter from quarter-wave to half-wave, which fundamentally alters the passband characteristics. This parameter modification achieves flatter passband response and lower insertion loss by creating more favorable impedance matching and resonance conditions, while the filter design remains relatively simple.
Solution Approach 2:
The patent adds full grounding as an additional dimensional feature to the resonator structure, transforming partial grounding to complete grounding at both ends. This dimensional enhancement improves passband flatness and low-loss performance by creating more stable electromagnetic field distribution without significantly complicating the filter design.
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 solution results in reduced insertion loss and improved frequency selectivity, achieving a higher Q factor and better passband performance compared to traditional quarter-wave resonators.
Implementation Method 1
distributed element RF filters comprising grounded half-wave resonators
Data Source
AI summary
A distributed element radio frequency (RF) filter includes one or more fully grounded half-wave resonators located between first and second resonators electrically coupled to corresponding input/output (I/O) interfaces proximate corresponding ends of a dielectric substrate. Each of the one or more half-wave resonators comprise a U-shaped or omega-shaped resonator portion located between first and second end portions electrically connected to a ground plane at a common side of the substrate. Each resonator has an electrical length that is nominally one-half a wavelength of a center frequency of the filter. The filter can optionally include a conductive cover over the resonators.