RF Transmission Lines with Plastic Dielectric Spacers
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Solution Overview
Problem
Conventional RF transmission lines, such as microstrip and stripline transmission lines, face challenges with high dielectric losses, impedance matching, and passive intermodulation (PIM) distortion due to the use of lossy materials and thin conductive traces, which limits their performance in wireless communications systems.
Innovation Solution
The use of RF transmission lines with a conductive ground plane, a conductive strip, and one or more plastic strips with a high dielectric constant (at least 2.0) and low dissipation factor, maintained by dielectric fasteners, which reduces physical length while maintaining the required electrical length and impedance matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional microstrip or stripline transmission lines are used, then the structure is simple and easy to manufacture, but the dielectric losses are high and performance is limited
Solution Approach 1:
The patent changes the dielectric parameter by using air as the insulating medium instead of conventional dielectric materials. This substitution reduces dielectric losses while maintaining the transmission line structure, achieving lower energy loss without significantly complicating the manufacturing process.
Solution Approach 2:
The patent extracts the dielectric material from the transmission line structure, replacing it with air. This removal of the lossy dielectric medium eliminates the source of dielectric losses while preserving the essential conductive elements and their geometric arrangement.
2Loss of energy
If air-insulated transmission lines are used, then dielectric losses are reduced, but the physical length required is longer
Solution Approach 1:
The patent modifies the effective dielectric constant by introducing dielectric spacers that create a non-uniform dielectric environment. This changes the propagation characteristics of the transmission line, allowing for reduced physical length while maintaining the required electrical length and signal integrity.
Solution Approach 2:
The patent introduces dielectric spacers as intermediary elements between the conductive elements and the air medium. These spacers locally modify the electric field distribution and effective dielectric constant, enabling compact design without sacrificing performance.
3Volume of moving object
If thin conductive traces are used, then the transmission line structure is compact, but PIM distortion increases
Solution Approach 1:
The patent changes the physical parameters of the conductive elements by using thicker traces and optimized geometries. This increases the current-carrying capacity and reduces surface resistance, thereby minimizing passive intermodulation distortion while maintaining a relatively compact overall structure through optimized layout.
Solution Approach 2:
The patent employs composite construction with thick conductive layers on low-loss substrates, combining materials and structures that simultaneously achieve compact dimensions and low PIM distortion through optimized material properties and geometric configuration.
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 achieves comparable insertion loss and return loss performance to air-insulated microstrip transmission lines with a shorter physical length, suitable for high-power RF signals and filters, allowing for smaller and more complex filter designs with improved power handling and reduced PIM distortion.
Implementation Method 1
one or more plastic strips disposed between the conductive ground plane and the conductive strip, the one or more plastic strips having a combined length that is at least half a length of the conductive strip
Data Source
AI summary
RF transmission lines that include a conductive ground plane, a conductive strip that extends above the ground plane, one or more plastic strips disposed between the conductive ground plane and the conductive strip, the one or more plastic strips having a combined length that is at least half a length of the conductive strip, and a plurality of dielectric fasteners that maintain the conductive strip at a predetermined distance above the conductive ground plane.