design techniques for high power rf coaxial cable...
TRANSCRIPT
Proprietary
Design Techniques for High Power RF Coaxial Cable Assemblies
Tony Martiniello
Chief Technology Officer
TRU Corporation © 2012. All rights reserved.
Proprietary
Primary Considerations
Primary
Considerations
Application
Prioritizing-Trade-offs
Performance
Electrical-Mechanical-Environmental
Cable-Connector-Attachment
Component Design
TRU Corporation © 2012. All rights reserved.
Proprietary
Typical High Power RF Applications
Semiconductor
Wafer Fabrication Equipment
Broadcast
Industrial Equipment
Medical Imaging
EMI / RFI Testing
Aerospace
TRU Corporation © 2012. All rights reserved.
Proprietary
Application Consequences
Dielectric material
Center conductor
Dielectric
TRU Corporation © 2012. All rights reserved.
Proprietary
Performance Assessment / Analysis
ELECTRICAL MECHANICAL ENVIROMENTAL
Frequency Flexibility Temperature
Attenuation Bend Radius Moisture
RF Power Size Altitude
Shielding Weight Radiation
Phase Stability Crush/Pull Strength Fluid Resistance
TRU Corporation © 2012. All rights reserved.
Proprietary
RF Coaxial Cable Design
Typical Coaxial Cable Constructions Single shield, extruded (PE) dielectric Double shield, extruded (PE or PTFE) dielectric VP = 66% VP = 66% to 70%
Expanded PTFE dielectric, strip & round shields Corrugated Coaxial Cable VP = 76 to 82 VP = 80 to 85
TRU Corporation © 2012. All rights reserved.
Proprietary
Cable Constructions and Power
Typical Center Conductor Constructions
Solid Stranded (7) Stranded (19)
Attenuation Lowest Moderate Highest
Power Highest Moderate Lowest
Flexibility Lowest Moderate Highest
Torque Highest Moderate Lowest
Cost Lowest Moderate Highest
Typical Dielectric Construction
Typical Jacket Constructions
PE PE PTFE PTFE
Solid Foamed Solid Expanded
Attenuation Best Moderate Low Best
VP Lowest Highest Low High
Flexibility Lowest Low Moderate Best
Temp Low Low Moderate Best
Crush Best Low High Moderate
Weight High Low Moderate Low
Cost Low Low Moderate Highest
PVCPoly-
F/G Braid FEP Corrugatedurethane
Flexibility Good Good Best Good Low
Temp Low Low High High High
Moisture Good Good Poor Good Good
Chemicals Low Low Low High Low
Flame Good Low Moderate Good Good
Cracking Worst Low N/A Good Low
Cost Low Low Highest Moderate Moderate
TRU Corporation © 2012. All rights reserved.
Proprietary
RF Coaxial Cable Reference Guide
TRU Corporation © 2012. All rights reserved.
Proprietary
Cable Power Capabilities
TRU Corporation © 2012. All rights reserved.
Proprietary
Selecting a Connector Interface
TRU Corporation © 2012. All rights reserved.
Proprietary
RF Connector Design
• Material Selection
– Common Dielectric - Teflon®
– High Power Options – Fluoroloy, BN
• Construction
– Mechanical Captivation vs. Epoxy
– Swept vs. Miter Angles
• Geometry
– Line Size Match - Connector & Cable
– Telescope / Overlap Insulators
TRU Corporation © 2012. All rights reserved.
Proprietary
RF Connector Power Handling
TRU Corporation © 2012. All rights reserved.
Proprietary
Cable / Connector Attachment Design
• Electrical
– Matched line size of cable/connector
– Voltage arc protection
• Mechanical
– Pull / torque strength (belt & suspenders)
– Clamp attachment, TRUtie™ method
• Environmental
– Weather
– Altitude
TRU Corporation © 2012. All rights reserved.
Proprietary
Summary
• Application Review
– Understand as much as possible of actual operating environment
or proceed at your own risk
• Performance Assessment
– You can’t have it all – prioritize the “must have” & “nice to have”
• Design Considerations
– Holistic Design Approach: Cable – Connector - Attachment
TRU Corporation © 2012. All rights reserved.
Proprietary
High Power RF Coax Assemblies
Conclusion:
Proper design considerations can result in a flexible RF cable
assembly solution for high power application as high as 50 – 100 kW.
TRU Corporation © 2012. All rights reserved.