3.5 mm Coaxial Cable Adapters Overview

The 3.5 mm Coaxial Connector is a widely used standardized coaxial connector type with some interesting features. These features make the 3.5 mm Coaxial Connector a very common connector type, which is why there are a plethora of 3.5 mm Coaxial Adapters. The 3.5 mm Coaxial Connector is designed to be relatively rugged and uses an air-dielectric as opposed to physical dielectric like many other coaxial connector standards. This coaxial connector achieves mode free operation to 34 GHz. As the name implies, the 3.5 mm Coaxial Connector features a 3.5 mm outer conductor diameter.

An interesting feature of this connector standard is that 3.5 mm connectors are also inter-mate compatible with SMA and 2.92 mm coaxial connectors. This means that a quality 3.5 mm connector should be able to mate successfully with a SMA connector, albeit the frequency range and VSWR would be limited by the quality of the SMA connection. Conversely, a 3.5 mm Coaxial Connector can also mate with a 2.92 mm Coaxial Connector, where the 3.5 mm connector would be the limiting factor in the frequency range. Another factor to consider is that SMA connectors are made for a wide variety of applications at various quality levels, and a mating a quality 3.5 mm connector with poor quality SMA connector might result in excessive wear and degrading of the 3.5 mm connector.

To avoid this, it is generally recommended in applications and use cases that are concerned with performance and ruggedness to use the appropriate coaxial adapter instead. This is why, even though 3.5 MM, SMA, and 2.92 mm coaxial connectors are inter-mate compatible, there are still coaxial cable adapters available that allow for interconnect between these coaxial standards. Another note is that some SMA connectors are reverse polarity, like those used in many Wi-Fi routers/access points and cellular modems, and a special adapter that mates with reverse polarity SMA is needed.

Even with like coaxial connector types it is often advisable to use coaxial adapters on equipment ports that experience a high cycle rate. For instance, VNA or signal analyzer test ports may undergo several cycles a day, which means it is easily possible to hit ~1000 cycles after only 1 year of use. This rate of wear would mean that a VNA/spectrum analyzer would need to be factory refitted for new ports every year, and this process could take weeks or months out of the machine’s uptime. A relatively inexpensive coaxial adapter such as the many 3.5 mm coaxial adapters could avoid this maintenance need entirely.

Important Coaxial Adapter Electrical Specifications Performance Parameters & Features

Frequency Range [Hz]
VSWR
Insertion loss [dB]
Power handling, maximum [dB]
Impedance [Ohms]
Shielding rating [dB]
Interface type/gender
Polarity {standard or reverse]
Outer conductor material
Dielectric material
Dielectric withstand voltage [V]
Inner conductor material
Operating temperature range [degrees Celsius]
Orientation/shape [inline, bend]
Mating cycle rating
Inter-mate capability
Size
Weight