Semi-Rigid Coax Sizes Guide: 0.034, 0.047, 0.086, 0.141 and 0.250 Inch

Semi-rigid coaxial cable is commonly identified by its nominal outside diameter (OD). Sizes such as 0.034 inch, 0.047 inch and 0.141 inch refer to the cable's outer diameter, not the center conductor size.

The right cable size depends on the required impedance, operating frequency, cable length, attenuation, available installation space, connector type and environmental requirements. Smaller cables are useful for compact routing, while larger constructions can provide lower attenuation and greater power-handling capability when other design factors are comparable.

This guide compares common semi-rigid coax sizes and the key factors to consider when selecting a cable for RF and microwave applications.

Common Semi-Rigid Coax Sizes at a Glance

Hongsen Cable supplies semi-rigid coaxial cable from 0.034 inch (0.86 mm) to 0.250 inch (6.35 mm), with PTFE and LD PTFE dielectric options and multiple conductor and outer conductor materials. Impedance options vary by size and model.

The industry commonly uses the "0.086 inch" designation. Hongsen Cable's corresponding series has a nominal outside diameter of 0.0865 inch (2.20 mm).

What Does Semi-Rigid Coax Size Affect?

Cable diameter is one of several factors that determine the overall performance and usability of a semi-rigid coaxial cable.

• Installation space: Smaller cables require less routing space and are easier to integrate into compact RF modules and enclosures.

• Attenuation: For comparable cable constructions, larger diameters generally have lower attenuation than smaller sizes.

• Power handling: Larger cable constructions may support higher power levels, depending on the specific design and operating frequency.

• Forming and routing: Smaller cables are suitable for compact layouts, but semi-rigid cable must be formed carefully to avoid deformation of the outer conductor.

• Connector compatibility: The connector must match the cable OD, impedance and assembly configuration.

• Materials: The same nominal size may be available with different dielectric, center conductor and outer conductor materials.

Cable diameter should therefore be considered together with the electrical and mechanical requirements of the application.

0.034 Inch and 0.047 Inch: Compact RF Assemblies

The 0.034 inch and 0.047 inch sizes are used where installation space is limited. Both are suitable for compact RF modules, microwave assemblies and internal point-to-point interconnects.

0.034 Inch Semi-Rigid Coax

With an OD of approximately 0.86 mm, 0.034 inch is one of the smallest commonly available semi-rigid coax sizes.

Hongsen's 0.034 inch range includes 50Ω configurations with PTFE dielectric and seamless copper, tin-plated copper or silver-plated copper outer conductors. A 10Ω configuration is also available for specialized impedance requirements.

Common applications:

• Compact RF and microwave modules

• Space-constrained internal interconnects

• Formed RF connections

• Specialized low-impedance designs

Confirm cable length, attenuation, forming requirements and connector compatibility before selecting this size.

0.047 Inch Semi-Rigid Coax

The 0.047 inch size has an OD of approximately 1.19 mm. It remains compact while providing more mechanical robustness than 0.034 inch cable.

Hongsen offers 50Ω 0.047 inch models with PTFE dielectric and seamless copper, tin-plated copper or silver-plated copper outer conductors.

Common applications:

• RF module interconnects

• Compact microwave assemblies

• Internal RF connections

• Space-constrained electronic equipment

Choose between 0.034 and 0.047 inch based on available space, attenuation, forming requirements and connector configuration.

0.086 Inch (0.0865 Inch): A Versatile RF and Microwave Size

The 0.086 inch designation is widely used in RF and microwave engineering. Hongsen's corresponding cable family has a nominal OD of 0.0865 inch (2.20 mm).

Hongsen's 0.0865 inch range includes:

• 25Ω, 50Ω and 75Ω impedance options

• PTFE and selected LD PTFE dielectric constructions

• Seamless copper, tin-plated copper, silver-plated copper and tin-plated aluminum outer conductors

• Silver-plated copper and silver-plated copper-clad steel center conductor options

Common applications:

• RF and microwave assemblies

• Test and measurement equipment

• Wireless communication equipment

• Internal equipment interconnects

• Designs requiring different impedance or conductor configurations

For a specific application, check the individual model's attenuation, operating frequency, power rating and connector compatibility rather than selecting by OD alone.

0.141 Inch and 0.250 Inch: Larger-Diameter Options

Larger semi-rigid coax sizes are generally considered when installation space is available and lower attenuation, mechanical robustness or power-handling capability is more important than minimum cable size.

0.141 Inch Semi-Rigid Coax

With an OD of approximately 3.58 mm, 0.141 inch cable provides a larger transmission structure for RF and microwave assemblies.

Hongsen supplies 0.141 inch models in 25Ω, 35Ω, 50Ω and 75Ω configurations, with multiple center conductor and outer conductor material options.

Common applications:

• Test and measurement equipment

• RF and microwave assemblies

• Longer internal RF routing paths

• Applications where attenuation and mechanical robustness are important

• Specialized impedance requirements

Compare the actual attenuation and power specifications of the selected model before choosing 0.141 inch over a smaller size.

0.250 Inch Semi-Rigid Coax

With a nominal OD of approximately 6.35 mm, 0.250 inch is the largest size covered in this guide.

Hongsen offers 50Ω and 75Ω versions with PTFE dielectric and copper, tin-plated copper, silver-plated copper or tin-plated aluminum outer conductor options.

Common applications:

• RF and microwave systems where low attenuation is important

• Higher-power RF applications, subject to model specifications

• Larger equipment enclosures

• Fixed installations with sufficient routing space

The larger OD requires more installation clearance and a larger routing path. Confirm the cable's forming method, connector compatibility and rated performance before ordering.

How to Choose the Right Semi-Rigid Coax Size

1. Match the System Impedance

• 50Ω is the most common choice for RF, microwave, wireless communication and test equipment.

• 75Ω is used for specific video, broadcast and measurement applications.

Selected Hongsen cable sizes are also available in 10Ω, 25Ω and 35Ω configurations for specialized designs.

Match the cable impedance to the system to minimize reflections and maintain the required transmission performance.

2. Check Frequency, Cable Length and Attenuation

Compare the specified attenuation at the actual operating frequency and cable length. Do not estimate cable loss from diameter alone.

For longer cable runs or higher-frequency applications, attenuation can become a major selection factor.

3. Check Installation Space

Consider the complete cable route, including:

• Cable OD

• Routing clearance

• Bend path

• Connector termination area

• Assembly access

Smaller sizes are useful for compact equipment, while larger sizes require more installation space.

4. Check Power and Mechanical Requirements

If power handling or mechanical robustness is important, compare the rated performance of the specific cable models rather than selecting by diameter alone.

Semi-rigid cable also requires controlled forming. The forming method and allowable bend requirements should be considered during assembly design.

5. Confirm Materials and Environmental Requirements

Check the dielectric, center conductor and outer conductor materials according to the electrical and environmental requirements of the application.

Available constructions may include PTFE or LD PTFE dielectric, copper or plated copper conductors, and different outer conductor materials.

6. Verify Connector Compatibility

Semi-rigid coax connectors are size- and configuration-specific. Confirm the cable OD, impedance, connector interface and termination method before ordering.

Other Available Semi-Rigid Coax Sizes

In addition to the main sizes above, Hongsen also offers:

• 0.043 inch (1.09 mm) semi-rigid coaxial cable, including a 10Ω configuration

• 0.090 inch (2.29 mm) semi-rigid coaxial cable, including a 25Ω configuration

These sizes provide additional options when a 0.034, 0.047, 0.0865, 0.141 or 0.250 inch cable does not match the required impedance, space or construction requirements.

Request a Semi-Rigid Coax Recommendation

The appropriate semi-rigid coax size depends on the complete electrical and mechanical requirements of the application.

When requesting a recommendation or quotation, provide:

• Required impedance

• Operating frequency

• Cable length

• Required attenuation or loss budget

• Available installation space

• Operating environment

• Center and outer conductor requirements

• Connector type and interface

Hongsen Cable can provide semi-rigid coaxial cable in different sizes, impedances and material configurations for RF and microwave applications.