Coaxial-Microstrip Conversion Circuit for Low-Reflection Ground Transition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High frequency signal reflections occur when coaxial and microstrip lines are connected due to discontinuity in propagation mode, which increases with frequency and vertical distance between ground conductors.
Innovation Solution
A coaxial microstrip line conversion circuit design that includes a housing part with a protrusion and a recessed microstrip line substrate, where the ground conductive part is bent at the cut surface, reducing the vertical distance between the ground conductors and improving signal continuity by bonding the central conductor and microstrip line with a solder layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the distance between the ground outer conductor part of the coaxial line and the back surface ground conductive part of the microstrip line substrate increases, then the ease of assembly is improved, but the signal reflection increases due to propagation mode discontinuity
Solution Approach 1:
The ground conductive part is extended in the vertical dimension by forming a protrusion that fits into a recess on the housing part. This vertical extension allows the ground conductor to reach closer to the coaxial line ground outer conductor part, reducing the vertical distance and propagation mode discontinuity while still allowing horizontal placement flexibility for assembly.
Solution Approach 2:
The shape of the ground conductive part is changed from a flat plane to a three-dimensional structure with a protrusion. This parameter change in the ground conductor geometry enables it to bridge the gap between the coaxial line ground and the microstrip substrate, reducing the effective distance and improving signal transmission while maintaining assembly ease.
2Productivity
If the signal frequency increases, then the transmission capacity is improved, but the signal reflection increases due to propagation mode discontinuity
Solution Approach 1:
The ground conductive part is extended in the vertical dimension by forming a protrusion that fits into a recess on the housing part. This vertical extension allows the ground conductor to reach closer to the coaxial line ground outer conductor part, reducing the vertical distance and propagation mode discontinuity while still allowing horizontal placement flexibility for assembly.
Solution Approach 2:
The shape of the ground conductive part is changed from a flat plane to a three-dimensional structure with a protrusion. This parameter change in the ground conductor geometry enables it to bridge the gap between the coaxial line ground and the microstrip substrate, reducing the effective distance and improving signal transmission while maintaining assembly ease.
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 design effectively reduces signal reflections for frequencies above several GHz, maintaining a low voltage standing wave ratio up to 40 GHz, and suppresses warp in the microstrip line substrate, enabling efficient high-frequency signal transmission.
Implementation Method 1
The solder layer bonds the one end portion of the central conductor part and one end portion of the microstrip line
Data Source
AI summary
A coaxial microstrip line conversion circuit includes a housing part including a protrusion protruding into the interior, a microstrip line substrate, a coaxial line including central and ground conductor parts, and a solder layer. The microstrip line substrate includes a microstrip line, a dielectric body having a recess cut into a lower surface, and a ground conductive part bent along the cut surface. The microstrip line substrate is mounted to a bottom surface of the housing part so that the recess and the protrusion fit together. A vertical distance between a lowest position of the ground conductor part facing the central conductor part and a ground surface of the ground conductive part adjacent to the cut surface is less than a vertical distance between the lowest position and a ground surface of the ground conductive part adjacent to a region of the dielectric body where the recess is not provided.