Coupler with lumped components for wideband coupling consistency
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Solution Overview
Problem
Coupled-line couplers face limitations in achieving constant coupling over a wide band without using ferrite or high permeability materials, and their coupling rolls off when the length exceeds one-quarter wavelength, limiting octave bandwidth to +/â0.3 dB coupling ripple.
Innovation Solution
Incorporating a coil in one of the coupled lines with capacitors connected between the coil and circuit ground, which adds inductance and capacitance respectively, allowing for reduced length coupled sections and maintaining effective electrical length, thereby enhancing bandwidth and coupling consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the coupling length is increased to achieve constant coupling over a wide band, then the coupling consistency is improved, but the insertion loss increases and the device length becomes excessive
Solution Approach 1:
The coupler is divided into multiple coupled sections (e.g., three sections with different coupling coefficients) rather than using a single long coupled section. This segmentation allows each section to contribute differently to the overall coupling, enabling wideband constant coupling without requiring excessive total length, thereby reducing insertion loss while maintaining coupling consistency.
Solution Approach 2:
The coupling coefficient is varied across different sections of the coupler (e.g., strong coupling in the center section, weaker coupling in outer sections). By changing the coupling parameter across sections rather than using uniform coupling, the design achieves wideband constant coupling with reduced total length and lower insertion loss.
2Reliability
If the coupling length is increased to achieve constant coupling over a wide band, then the coupling consistency is improved, but the device length becomes excessive
Solution Approach 1:
The coupler is divided into multiple coupled sections (e.g., three sections with different coupling coefficients) rather than using a single long coupled section. This segmentation allows each section to contribute differently to the overall coupling, enabling wideband constant coupling without requiring excessive total length.
Solution Approach 2:
The coupling coefficient is varied across different sections of the coupler (e.g., strong coupling in the center section, weaker coupling in outer sections). By changing the coupling parameter across sections rather than using uniform coupling, the design achieves wideband constant coupling with reduced total length.
3Adaptability or versatility
If ferrite or high permeability materials are used to achieve greater than octave bandwidth, then the bandwidth is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The design replaces expensive ferrite or high permeability materials with conventional conductors and dielectrics. By using standard, easily manufactured materials instead of specialized magnetic materials, the device achieves comparable or superior bandwidth performance with reduced complexity and manufacturing difficulty.
Solution Approach 2:
Instead of changing materials to achieve bandwidth, the design changes the coupling coefficient distribution across sections. This parameter-based approach achieves wideband performance using conventional materials, avoiding the complexity associated with ferrite or high permeability materials.
4Reliability
If the coupling length is increased to achieve constant coupling over a wide band, then the coupling consistency is improved, but the directivity deteriorates
Solution Approach 1:
The coupler is divided into multiple coupled sections with different coupling coefficients. This segmentation allows precise control of coupling in each section, achieving constant coupling over wide bandwidth while maintaining high directivity through optimized section design rather than relying on a single long coupled section.
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 achieves a compact design with reduced insertion loss and increased power handling capability, maintaining low coupling variation across a wide frequency range, achieving a nominal â25 dB tap with improved directivity and isolation.
Implementation Method 1
A coil extending around an axis may be formed in the first conductor. At least a portion of the coil may be between the first and second coupled sections.
Implementation Method 2
At least a first capacitor may be connected between a circuit ground and the first conductor at a position of the coil between and spaced from the first and second coupled sections.
Implementation Method 3
A pair of conductive lines are coupled when they are spaced apart, but spaced closely enough together for energy flowing in one to be induced in the other.
Data Source
AI summary
A coupled-line coupler having a coil in one of the coupled lines may include first and second conductors having at least first and second coupled sections in which the first and second conductors are closely coupled. A coil extending around an axis may be formed in the first conductor. At least a portion of the coil may be between the first and second coupled sections. A first portion of the first conductor may cross over a second portion of the first conductor when viewed along the axis. At least a first capacitor may be connected between a circuit ground and the first conductor at a position of the coil between and spaced from the first and second coupled sections.