SMA Connector

SMA stands for Sub-Miniature Version A. These coaxial RF connectors developed in the 1960s. The connector has a 50 Ω impedance. The impedance of the connection is 50. SMA connections are often used in hand-held radio and mobile phone antennas, as well as WiFi antenna systems. Microwave systems, hand-held radios, and mobile telephone antennas all employ the SMA connection. And, more recently, USB software-defined radio dongles and WiFi antenna systems. It’s also used a lot in radio astronomy, especially at higher frequencies (5 GHz and more).

The reverse-polarity SMA connection (RP-SMA or RPSMA) is a variant of the SMA connector specification that reverses the interface’s gender. This non-standard type SMA connection is the most popular reverse polarity RF connector and is used in WiFi and WLAN systems. The reverse polarity characteristic is achieved by using a reverse mating interface, where the male RP-SMA connection houses the female receptacle and the female/jack RP-SMA connector houses the centre pin.

An SMA Connector’s dielectric substance works as an insulator. Between the inner and outer conductors of the SMA Connector lies a dielectric/insulator. Air would be the ideal insulator, but we need something to hold the connector’s central pin in place. Meanwhile, the mating plane of SMA connections is commonly made of polytetrafluoroethylene (PTFE). The SMA connector’s impedance is affected by the dielectric used. Furthermore, frequent connections can cause the SMA connector to wear and tear, causing the connector’s impedance to change, increasing reflections and losses at the connection point and across the system. Most manufacturers mention the number of mating cycles as a result of this.