Dual Capacitively Coupled Coaxial to Air Microstrip Transition
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Solution Overview
Problem
Existing RF signal transmission technologies face challenges in maintaining impedance and minimizing passive intermodulation (PIM) at junctions between different transmission lines, particularly due to the need for solderable materials like brass or copper, which are costly and dense, while aluminum, a lighter and cheaper option, does not accept solder.
Innovation Solution
A dual capacitively coupled coaxial cable to air microstrip transition using a thin printed circuit board substrate and insulating surfaces to form an effective capacitive coupling, avoiding direct metal-to-metal contact and employing insulating materials like adhesive, tape, or anodized coatings to secure RF energy transfer without soldering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solderable materials like brass or copper are used to couple metal-to-metal compression interfaces, then reliable electrical connection is achieved, but material cost and density increase
Solution Approach 1:
The patent introduces an insulating material as an intermediary between the inner conductor and the microstrip ground plane. This insulating material with controlled dielectric properties enables electrical coupling through capacitance while physically separating the metal surfaces, eliminating the need for solderable materials like brass or copper.
Solution Approach 2:
The patent replaces the mechanical soldering process with a capacitive coupling mechanism. Instead of using solder to create metal-to-metal bonds, the system uses electric field coupling through an insulating barrier, substituting a mechanical/thermal joining process with an electromagnetic field-based solution.
2Quantity of substance
If aluminum is used instead of brass or copper, then material cost and weight are reduced, but solderability is lost
Solution Approach 1:
The insulating material serves as a mediator that enables electrical connection without requiring solderability. By placing a conductive layer on one side of the insulating material and coupling it capacitively to the other side, the system achieves electrical connectivity without needing to solder the aluminum components.
Solution Approach 2:
The patent changes the fundamental parameter of electrical connection from direct conductive contact (requiring solderability) to capacitive coupling through an insulator. This parameter change allows the use of aluminum and other non-solderable materials while maintaining electrical functionality.
3Reliability
If direct metal-to-metal contact is made at transmission line junctions, then electrical coupling is achieved, but passive intermodulation (PIM) increases
Solution Approach 1:
The insulating material acts as a mediator that separates metal surfaces while maintaining electrical coupling through capacitance. This physical separation eliminates direct metal-to-metal contact points where PIM would be generated, while the capacitive coupling preserves the necessary electrical connectivity for signal transmission.
Solution Approach 2:
The patent converts the potential harm of direct metal contact (PIM generation) into a benefit by using the insulating material's dielectric properties to create capacitive coupling. The insulator that physically separates the metals also creates the capacitive effect needed for RF signal coupling, turning a limitation into an advantage.
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 solution provides a cost-effective, reliable, and PIM-minimized transition that maintains electrical coupling, reduces material costs by using aluminum, and improves thermal dynamics by preventing direct metal contact, resulting in stable and repeatable solder joints with improved electrical and mechanical properties.
Implementation Method 1
a first side of the insulating surface is affixed to a first portion of the printed circuit board... the second portion of the printed circuit board is electrically connected to an inner conductor of a coaxial cable
Implementation Method 2
an insulating surface to form an effective capacitive coupling transition that couples RF energy from a center conductor of a coaxial cable to an air microstrip
Data Source
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AI summary
A transmission line transition that couples RF energy between a coaxial cable and an air dielectric microstrip is provided. In some embodiments, the transition can combine a thin printed circuit board substrate and an insulating surface to form an effective capacitive coupling transition that can couple RF energy from the center conductor of a coaxial cable to an air microstrip. In some embodiments, the transition can include an insulating system affixed to a metallic surface, and the insulating system can secure an airstrip conductor in close proximity to an inner conductor of a coaxial cable to capacitively couple the airstrip conductor to the inner conductor of the coaxial cable. In some embodiments, the transition can employ a metallic body coated with an insulating surface to capacitively couple RF energy from the center conductor of the coaxial cable to the air microstrip.