AmphenolRF-AnsoftPatnersInDesign

Optimizing RF Connector Design Using HFSS TDR Capability
Jian Fu Principal RF Engineer Amphenol RF
Agenda
Amphenol RF Design Capabilities Optimizing RF Connector Design Using HFSS TDR Capability
Design Goal HFSS Model of Initial Design Simulation Results TDR Results Analysis Results Comparison Between Initial and Final Design
Q&A
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Amphenol RF Design Capabilities
3D Mechanical Design (PRO/E) 3D Mechanical Analysis
3D High Frequency Structure Simulator Analysis (ANSOFT)
Dedicated Model Shop Electrical Test & Measurement (Vector Network Analyzers, IMD) Environmental Screening (temperature, humidity, corrosion)
Design Goal
SMA Jack Receptacle Originally designed to work up to 8GHz VSWR 1.1+0.01*Freq. (in GHz) Extended Freq. to 12.4GHz, VSWR 1.224 max @ 12.4GHz
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HFSS Model of Initial Design
Simulation Results of Initial Design VSWR
Initial Model Simulated up to 12.4GHz VSWR significantly over the spec above 9GHz Perform Time Domain Sweep to see the reflections within the connector as a function of distance or time and Reveal the discontinuities that impact electrical performance the most
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Simulation Results of Initial Design TDR
Simulation Results of Initial Design TDR
Capacitive discontinuity at the knurl High impedances at the 2 compensation steps Normally, it is desirable to have inductive compensation steps in order to compensate for parasitic capacitances introduced at the transition in line size, but it appears from the TDR plot that they are too inductive and need to be reduced.
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Simulation Results After Tuning Compensation Steps – VSWR
Tuning feature in HFSS allows us to conveniently vary the dimensions manually and see the effects of our changes Using OPTIMETRICS automates the tuning process Vary the length of the compensation steps and chose the length that gave the best overall VSWR performance
Comparison of Simulation Results Between Initial and Revised Design - TDR
Initial Design
Revised Design
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TDR Results Analysis
Results: The inductances due to compensation steps are decreased, but the capacitance from the knurl is still significant. Constraint: The knurl can not be eliminated for its anti-rotation purpose Solution: To put groove in insulator around the knurl to achieve 50 Ohm impedance
Complication: asymmetric insulator, non-standard part, hard to assembly
Solution: To shorten the length of the knurl 20%
Complication: reduced anti-rotation force
Comparison of Simulation Results Between Initial and Final Design - TDR
Initial Design
Final Design
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Comparison of Simulation Results Between Initial and Final Design - VSWR
Initial Design
Final Design
Conclusion
By fully utilizing all of the capabilities of ANSOFT HFSS, we are able to optimize the performance of our connectors in the shortest time possible. Careful analysis of the time and frequency domain simulation results, along with the utilization of the tuning and optimization capabilities of the software, allows Amphenol RF to quickly deliver the best performing connectors.
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Thanks for your attention!
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