Directional Coupler With Switchable Sub-Lines For Wideband Loss Reduction
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Solution Overview
Problem
Directional couplers face excessive insertion loss when operated over wide frequency bands due to fixed coupling degrees between main and sub-lines, leading to suboptimal performance at high frequencies.
Innovation Solution
Incorporating multiple sub-lines with different coupling degrees and lengths, along with switch circuits and variable termination circuits, to selectively connect sub-lines to the main line and termination circuits, allowing for adjustable coupling and reduced insertion loss across a wide frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a single sub-line with fixed coupling degree is used, then the coupling degree can be optimized at a specific frequency, but the insertion loss increases excessively when operating over a wide frequency band
Solution Approach 1:
The patent divides the single sub-line into multiple sub-lines (first sub-line and second sub-line), each with different coupling degrees and optimized for different frequency ranges. This segmentation allows the directional coupler to maintain low insertion loss across a wide frequency band by selecting the appropriate sub-line for the operating frequency.
Solution Approach 2:
The patent introduces switch circuits that dynamically select which sub-line to connect based on the operating frequency. This dynamic switching capability enables the system to adapt to different frequency conditions, maintaining optimal coupling and minimizing insertion loss across the entire frequency band.
2Reliability
If the coupling degree between main line and sub-line is fixed, then the coupling can be optimized at low frequency, but the coupling becomes excessively high at high frequency resulting in high insertion loss
Solution Approach 1:
The patent creates different local coupling characteristics by designing multiple sub-lines with different coupling degrees. The first sub-line has a coupling degree optimized for low frequencies, while the second sub-line has a coupling degree optimized for high frequencies. This local quality differentiation ensures optimal coupling performance at each frequency range without excessive insertion loss.
Solution Approach 2:
The patent changes the coupling parameter by selecting different sub-lines based on frequency. The switch circuit alters which sub-line is connected, effectively changing the coupling degree parameter to match the operating frequency, thereby maintaining reliable coupling while preventing excessive insertion loss.
3Adaptability or versatility
If multiple sub-lines with different coupling degrees are added, then the frequency band adaptability is improved, but the device complexity increases
Solution Approach 1:
The switch circuit serves multiple functions: it selects which sub-line to connect, determines the signal transmission direction, and enables the directional coupler to operate across a wide frequency band. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity despite adding multiple sub-lines.
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
This configuration enables optimal coupling and minimizes insertion loss across a wide frequency range by selecting the appropriate sub-line and transmission direction, maintaining desired coupling levels and reducing unwanted signal transmission.
Implementation Method 1
a sub-line that is electromagnetically coupled to the main line
Data Source
AI summary
A directional coupler includes a main line through which a signal is transmitted, first and second sub-lines that are selectively coupled to the main line, and a common output port that outputs a detection signal generated by the signal transmitted through the main line, wherein a first degree of coupling between the main line and the first sub-line is different than a second degree of coupling between the main line and the second sub-line.