Directional Coupler Stray Capacitance Suppression
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Solution Overview
Problem
Conventional directional couplers experience degradation in characteristics due to stray capacitance when mounted on a substrate, as the line surfaces of the main and secondary lines face electrodes on the substrate, leading to signal interference and performance issues.
Innovation Solution
The directional coupler design features conductive main and secondary lines with thicknesses smaller than their widths, positioned within an insulating element body such that their axes do not intersect the mount surface, reducing the area facing substrate electrodes and minimizing stray capacitance. This configuration includes mounting terminals and a ground electrode for improved shielding and impedance adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the line surfaces of the main line and secondary line are parallel to the mount surface, then the directional coupler can be easily mounted, but stray capacitance occurs between the line surfaces and electrodes on the mount substrate, degrading the characteristics of the directional coupler
Solution Approach 1:
The patent changes the orientation of the line surfaces from parallel to the mount surface to perpendicular to the mount surface. This dimensional change in the arrangement of the main line and secondary line eliminates the parallel facing relationship between the line surfaces and electrodes on the mount substrate, thereby suppressing stray capacitance while maintaining ease of mounting through the perpendicular configuration
2Object-affected harmful factors
If the thickness of the first line portion is made smaller than the line width and the axis along the thickness direction does not intersect the mount surface, then the area facing substrate electrodes is reduced, suppressing stray capacitance, but the manufacturing precision requirements increase
Solution Approach 1:
The patent changes the thickness parameter of the first line portion to be smaller than its line width, and positions it such that the axis along the thickness direction does not intersect the mount surface. This parameter change reduces the effective area facing substrate electrodes, thereby suppressing stray capacitance. The insulating element body provides a stable structure that facilitates precise control of these parameters during manufacturing
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 effectively suppresses stray capacitance, preventing degradation of directional coupler characteristics and ensuring accurate mounting with reduced signal interference, thereby enhancing the performance and reliability of the device.
Implementation Method 1
a first line portion (11) and a second line portion (21) which are electromagnetically coupled to each other
Implementation Method 2
the area where the first line portion faces an electrode of the mount substrate can be reduced. This can suppress the occurrence of stray capacitance when the directional coupler is mounted on the mount substrate
Data Source
AI summary
A directional coupler includes an element body that is insulating, and a main line and a secondary line both disposed in the element body and being conductive. The directional coupler has a mount surface positioned on a mounted side when the directional coupler is mounted. A first line portion of the main line and a second line portion of the secondary line are electromagnetically coupled to each other. The first line portion has a thickness smaller than a line width of the first line portion, and is disposed in the element body in such a manner that an axis along a thickness direction of the first line portion does not intersect the mount surface.