Eccentric Vertical-Transition Structure for High-Frequency Insertion Loss
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Solution Overview
Problem
Conventional vertical transitions between coaxial cables and microstrip lines experience significant insertion loss due to differing electromagnetic field distributions and resonant responses at high frequencies, limiting their 1-dB passband and making them unsuitable for high-frequency applications.
Innovation Solution
A vertical-transition structure featuring an eccentric design with a microstrip line, a metallic ring, and a coaxial connector, where the center conductor is positioned eccentrically within the through hole and extends through a metallic ring to minimize resonant dips and improve electromagnetic field distribution alignment, reducing insertion loss and increasing the 1-dB passband.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional flange-mount coaxial connector is used to connect coaxial cable and microstrip line, then vertical connection is established, but severe insertion loss occurs at high frequencies due to different electromagnetic field distributions
Solution Approach 1:
The patent applies asymmetry by positioning the center conductor eccentrically within the through-hole of the substrate, rather than at the geometric center. This asymmetric positioning allows the center conductor to be closer to the microstrip signal line, creating a more gradual transition of electromagnetic field distribution between the coaxial connector and microstrip line, thereby reducing insertion loss at high frequencies while maintaining vertical connection reliability
Solution Approach 2:
The patent changes the geometric parameters of the transition structure, specifically the position of the center conductor within the through-hole. By adjusting the eccentricity parameter (distance from the geometric center), the electromagnetic field distribution is optimized to reduce the abrupt change between different transmission line types, thereby reducing insertion loss while maintaining connection reliability
2Device complexity
If a simple vertical connection structure is used, then device complexity is reduced, but resonant response of the coaxial connector causes insertion loss at higher frequencies
Solution Approach 1:
The asymmetric positioning of the center conductor within the through-hole modifies the resonant characteristics of the coaxial connector by changing the boundary conditions of the electromagnetic field. This simple asymmetric modification suppresses the resonant response that causes insertion loss at higher frequencies without significantly increasing device complexity
Solution Approach 2:
By changing the geometric parameter of the center conductor position (eccentricity), the resonant frequencies and field distribution of the coaxial connector are modified. This parameter change suppresses harmful resonant responses that cause insertion loss, achieving improved high-frequency performance with minimal structural modification
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 proposed structure significantly reduces insertion loss and expands the 1-dB passband from 0 to 27 GHz, enhancing the vertical transition's performance for high-frequency applications by smoothing electromagnetic field transitions and mitigating resonant responses.
Implementation Method 1
due to different electromagnetic field distributions of the two different transmission lines, 'insertion loss' is introduced at their joint
Implementation Method 2
The resonant response of the coaxial connector at higher-order modes also leads to the insertion loss of the vertical transition at high frequencies
Data Source
AI summary
A vertical-transition structure comprises a microstrip line and a combination of a coaxial connector and a metallic ring underneath the microstrip line. A first through hole is created next to the microstrip line and near one end of its signal line. The metallic ring has a second through hole. The coaxial connector has a center conductor including an extended portion to be inserted into the second through hole via its center, and subsequently through the first through hole to connect to the signal line vertically. Specially, the extended portion is not inserted through the center of the first through hole. The present structure can improve the high-frequency insertion loss of the vertical transition caused by the sudden change of electromagnetic field distributions from a coaxial line to a microstrip line and the resonant response of the coaxial connector, and therefore, increase the 1-dB transmission passband of the vertical transition substantially.