Directional Coupler Flat Frequency Response via Segmented Sublines
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Solution Overview
Problem
Conventional directional couplers suffer from a non-flat frequency response, leading to increased coupling with frequency, making it difficult to maintain consistent signal transmission across a wide frequency band, particularly in mobile communication systems using Carrier Aggregation technology.
Innovation Solution
A directional coupler design featuring multiple subline sections and matching sections with distinct phase-changing characteristics, including inductors and capacitors, to create two attenuation poles, thereby reducing frequency-dependent coupling changes across a wider band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional directional coupler is used, then the device is simple in structure, but the coupling increases with frequency resulting in non-flat frequency response
Solution Approach 1:
The subline is divided into multiple subline sections (first, second, third subline sections) with different coupling strengths to the main line. This segmentation allows each section to contribute differently to the overall frequency response, enabling the creation of multiple attenuation poles that flatten the coupling characteristics across a wide frequency band.
Solution Approach 2:
Different subline sections are designed with different coupling strengths to the main line. The first subline section has strong coupling, while the second and third have weak coupling. This local variation in coupling quality creates distinct attenuation poles at different frequencies, achieving flat frequency response across the operating band.
2Stability of the object's composition
If a wideband capable directional coupler with multiple subline sections is used, then the frequency response is flattened, but the device complexity increases
Solution Approach 1:
Multiple subline sections with different coupling characteristics are combined into a single integrated structure. The first, second, and third subline sections are merged along the subline, each contributing to creating attenuation poles at different frequencies. This merging achieves flat frequency response while maintaining a unified device structure.
3Stability of the object's composition
If the subline is divided into multiple sections with different coupling strengths, then coupling stability across frequency is improved, but the manufacturing complexity increases
Solution Approach 1:
The coupling strength parameter is varied across different subline sections. The first subline section is designed with strong coupling parameters, while the second and third sections use weak coupling parameters. This parameter change approach allows achieving flat frequency response through controlled variations in coupling strength, which can be implemented through standard manufacturing techniques.
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 directional coupler achieves a more stable frequency response with reduced coupling changes over a wider frequency range, enhancing its suitability for multiple signal transmission in various frequency bands used in advanced mobile communication systems.
Implementation Method 1
The first matching section and the second matching section are configured to cause changes in phase of high frequency signals passing therethrough
Implementation Method 2
a first, a second and a third subline section (20A, 20B, 20C) each of which is formed of a line configured to be electromagnetically coupled to the main line (10)
Data Source
AI summary
A directional coupler includes: a main line connecting an input port and an output port; first to third subline sections each of which is formed of a line configured to be electromagnetically coupled to the main line; a first matching section provided between the first subline section and the second subline section; and a second matching section provided between the second subline section and the third subline section. The first and second matching sections are configured to cause changes in phase of high frequency signals passing therethrough, and have mutually different characteristics so as to create two attenuation poles in the frequency response of the coupling of the directional coupler.