The SMA connector(SubMiniature version A) is a 50 ohm coaxial connector. It is visually similar to an F type connector that is commonly used for audio/video communication, but has different dimensions, mechanical properties and is used for different applications such as RF communications up to 18 GHz. Due to its construction, SMA connectors provide a strong and durable connection that minimizes reflections, limiting attenuation, and makes it a great choice when working with microwave frequencies.

 

Key Takeaways

  • SMA connector dimensions are important when selecting, replacing, or designing RF cable assemblies.
  • SMA connectors use a threaded coupling interface for secure mating.
  • Standard SMA and RP-SMA connectors have different centre-contact configurations.
  • Standard SMA connectors commonly use a 1/4-36 UNS thread.
  • SMA connectors are widely used in RF, wireless, antenna, microwave, and test equipment.
  • Many SMA applications use 50-ohm RF systems, but the specific connector specification should always be verified.
  • Connector dimensions can vary depending on the mounting style, cable type, and manufacturer.
  • Always match the SMA connector to the coaxial cable, frequency range, impedance, and equipment interface.
  • When replacing an SMA connector, verify gender, polarity, thread, cable compatibility, mounting style, and dimensions.
  • For high-frequency applications, electrical specifications such as VSWR and insertion loss are as important as physical dimensions.
  • Outdoor installations may require connectors with suitable environmental protection.
  • Using the manufacturer's dimensional drawing and specifications is the most reliable way to confirm SMA connector compatibility.

 

 

SMA Male Connector

The SMA male connector is identified by inside 1/4″-36 threads and a 5/16″ hex nut. A standard polarity connector will have a male pin.

 


SMA Male Dimensions

  • Outer Diameter: 6.35mm
  • Inner Diameter: 4.59mm
  • Pin Diameter: .97mm
  • Pin Tip Diameter: .38mm

 

 

SMA Female Connector

The SMA female connector is identified by outside 1/4″-36 threads. A standard polarity connector will have a female sleeve.

 

 

SMA Female Dimensions

  • Outer Diameter: 5.49mm
  • Inner Diameter: 4.60mm
  • Pin Insert Diameter: 1.30mm

 

 

Reverse Polarity (RP) SMA Male Connector

The RP SMA male connector is identified by inside 1/4″-36 threads and a 5/16″ hex nut. It will not have a male pin, but will have a female sleeve.

 

 

RP SMA Male Dimensions

  • Outer Diameter: 6.35mm
  • Inner Diameter: 4.59mm
  • Pin Insert Diameter: 1.30mm

 

 

 

Reverse Polarity (RP) SMA Female Connector

The SMA female connector is identified by outside 1/4″-36 threads. A standard polarity connector will not have a female sleeve, but will have a male pin.

 

 

RP SMA Female Dimensions

  • Outer Diameter: 5.49mm
  • Inner Diameter: 4.60mm
  • Pin Diameter: .97mm
  • Pin Tip Diameter: .38mm

 

Identifying a RP SMA Connector

If you need help identifying the polarity of a SMA connector, please see this video.

 

Applications for SMA

SMA connectors are used to terminate flexible or rigid cable. They are used in a variety of military applications including testing, radar, and landing systems. They are also common for wireless or cellular applications such as base stations, satellite communications and antenna connectors.

 

Recommendations

 

For RF Applications

For RF applications, select an SMA connector based on the required frequency range, impedance, cable type, and connector configuration. Verify the manufacturer's specifications to ensure the connector can provide the required electrical performance.

For Wi-Fi and Wireless Equipment

SMA and RP-SMA connectors are commonly encountered in wireless and antenna applications. Before purchasing a replacement, verify whether the equipment requires standard SMA or reverse-polarity SMA, as the two configurations have different centre-contact arrangements.

For Coaxial Cable Assemblies

When building an SMA cable assembly, select a connector specifically designed for the coaxial cable being used. Matching the connector to the cable diameter and construction helps provide a secure mechanical connection and reliable RF performance.

For PCB Applications

For PCB-mounted RF connections, choose an SMA connector designed for the board layout and required mounting configuration. Verify the footprint, mounting style, frequency range, and mechanical dimensions before installation.

For Panel-Mount Applications

For equipment panels and enclosures, use a bulkhead or panel-mount SMA connector with dimensions that match the available mounting hole and hardware.

For High-Frequency Systems

For high-frequency RF systems, pay close attention to connector specifications rather than selecting a connector based only on physical size. Verify frequency rating, VSWR, insertion loss, impedance, and mating-interface specifications.

For Replacement Connectors

When replacing an SMA connector, compare the original connector's gender, polarity, cable compatibility, mounting style, thread configuration, and dimensions. This helps ensure the replacement will physically and electrically match the existing system.

For Outdoor Installations

For outdoor RF installations, choose an SMA connector with appropriate environmental protection and ensure the cable assembly is properly protected against moisture, dust, temperature changes, and mechanical stress.

 

Finding the Right SMA Connector or Adapter

ShowMeCables carries a wide selection of SMA connectors and adapters. No matter if you are working with thin cable like RG-178 or rigid cable like LMR-600 we have the fittings you need. Shop online to see our entire selection.

 

FAQs – Frequently asked questions

 

What are SMA connector dimensions?

SMA connector dimensions refer to the physical measurements of an SMA connector, including its mating interface, thread, centre contact, body diameter, and overall length. Exact dimensions can vary depending on the specific connector design and manufacturer.

What is an SMA connector?

An SMA connector is a threaded RF coaxial connector commonly used in wireless, antenna, microwave, test, and other high-frequency applications.

What size is an SMA connector?

SMA connectors have standardised mating-interface characteristics, but the overall dimensions can vary depending on whether the connector is cable-mounted, PCB-mounted, bulkhead-mounted, straight, or right-angle.