SMA Coaxial Attenuators Explained

The SubMiniature version A (SMA) coaxial connector standards is one of the most common coaxial connectors standards used in an extremely wide variety of low power RF applications. The SmA standard was originally designed to only operate from DC to 12 GHz, but there are now precision variants that often reach 18 GHz to 26.5 GHz. The SMA coaxial connector is also connector compatible with other coaxial connector standards, such as the K-connector and the 3.5mm connector. Hence, there are a wide variety of components, devices, and interconnect options available that use the SMA connector, including SMA Fixed Coaxial Attenuators.

What is an SMA Coaxial Attenuator?

A SMA coaxial attenuator is simply a coaxial connectorized attenuator with an SMA connector. This means that the internal parts of the SMA attenuator are an attenuator that is electrically connected to two SMA ports. Attenuators are available for all common coaxial connector’s standards, Due to the ubiquity of the SMA coaxial connector, however, there is a wide selection of various attenuator types and styles with SMA connectors, including fixed attenuators, high power attenuators, manually variable attenuators, continuously variable attenuators, step attenuators, and programmable attenuators.

SMA coaxial connectors have several variants designed to exceed the common SMA standard in frequency, power, environmental specifications, etc. As a result of this, there are even high power SMA connector versions that allow for high power SMA attenuators to 100 Watts or even more.

What are the Key Performance Specifications & Features of SMA Coaxial Attenuators?

Since an SMA coaxial attenuator is essentially just a coaxial connectorized attenuator with two coaxial ports, the key specifications for coaxial connectors and RF attenuators apply to these components. The main considerations are generally frequency range, power handling, attenuation level, and impedance. It is possible that some SMA coaxial attenuators are specified to a range of frequencies below that which is capable by the SMA connector for a given power handling.

Key RF SMA Coaxial Attenuator Performance Specifications

• Frequency range [Hz]
• VSWR [ratio]
• Insertion loss [dB] *lowest attenuation value
• Attenuation value(s) [dB]
• Step size [dB]
• Step type [toggle etc.]
• Impedance [Ohms]
• Velocity of propagation [%c]
• Power handling (CW, peak) [Watts]
• Attenuation accuracy [+/-dB]
• Connector type 1 and 2
• Temperature range of operation [deg C]
• Connector Specifications [MIL-SPEC etc.]
• Contact Material & Plating [beryllium copper, gold, etc.]
• Dielectric Type [Teflon, PTFE, etc.]
• Coupling Nut Material & Plating [passivated stainless steel, nickel, etc.]
• Body Material & Plating [passivated stainless steel, nickel, etc.]
• Heat Sink material & plating/coating [anodized aluminum, etc.]