Transmission Line Circuit Assemblies With Dielectric Plug Transitions
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Solution Overview
Problem
Current microwave devices face challenges in implementing low-cost, wideband mode-free impedance-invariant interconnections/transitions between transmission line circuits and external conductors, and maintaining continuous electromagnetic ground, which are crucial for harsh environments like satellite communication systems, leading to increased costs and time due to invasive tuning and validation processes.
Innovation Solution
A transmission line circuit assembly with a substrate layer, a dielectric plug, and a connecting pin, where the dielectric plug and connecting pin form an electromagnetic transition with an external conductor, using a dielectric filler and variable width transitional portion to achieve impedance matching and mechanical stress relief, reducing the need for invasive tuning and enhancing signal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional transmission line interconnections are used, then manufacturing is simpler, but impedance matching and signal integrity deteriorate in wideband applications
Solution Approach 1:
The interconnection structure is segmented into distinct functional portions: a first portion integrated with the transmission line circuit board, a second portion forming the external conductor interface, and a transitional portion connecting them. This segmentation allows each portion to be optimized independently for its specific function while maintaining overall impedance matching.
Solution Approach 2:
The transitional portion features a variable width design that changes locally along its length to provide impedance transformation. This local variation in geometry creates the necessary impedance matching characteristics without requiring complex structures throughout the entire interconnection.
2Manufacturing precision
If invasive tuning processes are applied, then impedance matching improves, but manufacturing time and costs increase
Solution Approach 1:
The impedance matching characteristics are built into the structure during manufacturing through the predetermined variable width transitional portion design. This preliminary incorporation of matching features eliminates the need for subsequent invasive tuning processes, thereby maintaining manufacturing precision while improving productivity.
3Reliability
If mechanical stress is applied to the connecting pin, then connection stability improves, but signal integrity deteriorates due to stress on the bond
Solution Approach 1:
A dielectric member is introduced as an intermediary element between the connecting pin and the transmission line circuit board. This dielectric member provides mechanical support and stress relief to the connecting pin while maintaining electrical isolation, thereby preserving signal integrity through the bond between the pin and board.
4Reliability
If the dielectric plug is positioned close to the transmission line trace, then electromagnetic coupling improves, but impedance control becomes difficult
Solution Approach 1:
The dielectric member features localized dielectric material placement with varying properties along its length. This local variation in dielectric characteristics allows optimization of electromagnetic coupling in certain regions while maintaining impedance control in other regions, resolving the contradiction between coupling strength and impedance precision.
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 provides efficient electromagnetic transitions with improved return loss and insertion loss, reducing manufacturing time and costs by minimizing mechanical stress and invasive tuning requirements, while maintaining signal integrity across a wide frequency range.
Implementation Method 1
the dielectric plug and connecting pin form an electromagnetic transition with an external conductor
Implementation Method 2
using a dielectric filler and variable width transitional portion to achieve impedance matching
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A transmission line circuit assembly 200 has a substrate layer 100 having a transmission line trace, further having a functional portion 128 and a transitional portion 124. An enclosure of the assembly houses the transitional portion 124 of the transmission line trace. A first surface 280 of a dielectric plug 272 is conductively coupled to an inner top surface of the enclosure. A second surface 288 of the plug 272 is aligned and spaced apart from the transitional portion 124 of the transmission line trace to define a gap 296 therebetween. An interfacing portion 320 of a connecting pin 312 is housed within the enclosure and bonded to the transitional portion 124. A connecting portion 328 of the pin 313 is connectable to an external conductor. The gap 296 may be filled with a dielectric material. The transitional portion 124, dielectric plug 272, dielectric filler 376 and connecting pin 312 form an electromagnetic transition providing tuning and matching of the function portion with the external conductor.