Directional Coupler Reactive Element Ground Conductor Phase Delay
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Solution Overview
Problem
Conventional directional couplers face issues with degraded directivity due to constraints on manufacturing, leading to a phase difference between even and odd mode operations when coupled line impedance is lower than terminal impedance, resulting in increased isolation and reduced coupling.
Innovation Solution
Incorporating a reactive element with a discontinuous structure in the ground conductor, which delays the phase by a quarter wavelength, ensuring the passing phase matches between even and odd mode operations, thus improving directivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the coupled line impedance is reduced to maximize coupling amount, then the coupling amount increases, but the passing phase at even mode operation leads against that at odd mode operation, causing phase difference and directivity degradation
Solution Approach 1:
A reactive element is introduced as an intermediary component connected to the ground conductor between the even-mode and odd-mode signal paths. This reactive element acts as a mediator that selectively adjusts the passing phase in one mode to compensate for the phase difference between even and odd modes, thereby restoring directivity while maintaining the reduced coupled line impedance for high coupling amount
Solution Approach 2:
The reactive element changes the electrical parameter (passing phase) of the signal path in even-mode operation. By adjusting the reactance value of the added component, the passing phase is modified to match between even and odd modes, resolving the phase difference issue without requiring changes to the coupled line impedance or physical dimensions
2Ease of manufacture
If manufacturing constraints are considered, then the coupled line impedance becomes lower than terminal impedance, but this causes phase difference between even and odd mode operations, degrading directivity
Solution Approach 1:
The reactive element serves as an intermediary that compensates for the directivity degradation caused by manufacturing constraints. Instead of requiring precise control of coupled line impedance to match terminal impedance, the reactive element is added to the ground conductor to adjust the passing phase and restore directivity, making the design more tolerant of manufacturing variations
Solution Approach 2:
Instead of trying to make the coupled line impedance equal to terminal impedance by adjusting physical dimensions (the conventional approach), the invention inverts the problem by keeping the manufacturing-friendly low impedance and using a reactive element to achieve the desired phase relationship, effectively solving the problem from the opposite direction
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 reactive element in the ground conductor effectively matches the passing phases between even and odd mode operations, reducing isolation and enhancing the directivity of the directional coupler even when coupled line impedance is lower than terminal impedance.
Implementation Method 1
a reactive element that is disposed in the ground conductor and is arranged directly below the first signal conductor and the second signal conductor, and that is comprised of a discontinuous structure that has a function of delaying a phase and that is small with respect to the one-quarter wavelength of an operating frequency
Data Source
AI summary
Disclosed is a directional coupler including a first hollow portion that is disposed in a first ground conductor and is arranged directly above a first signal conductor and a second signal conductor, and that is constructed of a discontinuous structure that has a function of delaying the phase and that is small with respect to the one-quarter wavelength of an operating frequency.