Coaxial-to-Microstrip Transition Using Metallic Ring to Suppress TE11 Mode
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Solution Overview
Problem
Transitions between coaxial cables and microstrip lines suffer from severe insertion loss due to discontinuity in electromagnetic field distributions and the excitation of the first higher-order mode (TE11 mode) of conventional coaxial connectors, leading to resonant responses and limited passband at higher frequencies.
Innovation Solution
A method involving a metallic ring and a conventional coaxial connector, where the metallic ring has a through hole, and a second dielectric body is used to fill the space between the center conductor and the external conductor, with specific calculation formulas to determine the inner radius of the through hole, allowing for the attenuation or elimination of the resonant response and improvement of the transition's frequency response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional coaxial connector is used for transition between coaxial cable and microstrip line, then the transition structure is simple and easy to manufacture, but severe insertion loss occurs at higher frequencies due to electromagnetic field discontinuity and excitation of the first higher-order mode
Solution Approach 1:
A metallic ring with a through hole is introduced as an intermediary component between the coaxial connector and the microstrip line. This metallic ring serves as a buffer structure that facilitates smooth electromagnetic field transformation and suppresses the excitation of higher-order modes, thereby reducing insertion loss at higher frequencies while maintaining ease of manufacture
Solution Approach 2:
The inner radius of the through hole in the metallic ring is precisely calculated using a specific formula to optimize the electromagnetic field distribution. By adjusting this geometric parameter, the transition structure achieves better field continuity and suppresses resonant responses, reducing insertion loss without complicating the manufacturing process
2Reliability
If the inner radius of the through hole in the metallic ring is not precisely calculated, then the manufacturing process is simpler, but the resonant response caused by the first higher-order mode cannot be effectively suppressed
Solution Approach 1:
The inner radius of the through hole is pre-calculated using a specific formula before the actual manufacturing process. This preliminary calculation ensures that the metallic ring will effectively suppress resonant responses and higher-order mode excitation, achieving reliable performance without requiring complex manufacturing processes or tight tolerances
3Loss of energy
If a buffer structure is added at the interface to transform electromagnetic field distributions, then insertion loss caused by abrupt field change is reduced, but the device complexity increases
Solution Approach 1:
A metallic ring with a through hole is introduced as an intermediary component between the coaxial connector and the microstrip line. This metallic ring serves as a buffer structure that facilitates smooth electromagnetic field transformation and suppresses the excitation of higher-order modes, thereby reducing insertion loss at higher frequencies while maintaining ease of manufacture
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 effectively reduces insertion loss and increases the 1-dB passband of the transition, enhancing signal propagation at high frequencies by eliminating the resonant response caused by the first higher-order mode, thereby improving the transition's performance.
Implementation Method 1
the second dielectric body, which is different from the first dielectric body... to fill up the space between the inner wall of the through hole and the center conductor
Implementation Method 2
the attenuation or even elimination of a resonant response caused by the excitation of the first higher-order mode of the conventional coaxial connector
Data Source
AI summary
A method to design and assemble a connector for the transition between a coaxial cable and a microstrip line involves in connecting a coaxial connector in series with a metallic ring to form a new coaxial connector, wherein the thickness of the metallic ring and the diameter of its through hole are important design parameters to determine the frequency response of the transition. By properly selecting their values and connecting the new coaxial connector to the microstrip line, a resonant response caused by the excitation of the first higher-order mode of the original coaxial connector is attenuated or eliminated from the frequency response.