What are SMA Connectors?

What are SMA Connectors?

SMA connector and RP–SMA connector, also known as coaxial connectors, are the standard for antenna connections. They form the minimum interfaces to coaxial cables by using a screwable coupling mechanism. Both are used in many devices and applications operating in the high-frequency range. Let’s discover what makes the SMA connectors standard different from RP-SMA connectors and which version you can use for which purpose.


Connectors for Coaxial Cables

The coaxial connectors are designed to fit into the structure of a coaxial cable. They also protect the inner conductor against electromagnetic influences by surrounding it with an insulating layer. The so-called dielectric, often made from plastic like polyethylene, provides both shielding and capacitive properties.

The structure of a coaxial connector is also affected by both the characteristic impedance and the impedance. The properties of the dielectric are the main determinants of the line characteristic impedance. It describes the relationship between a current moving in a similar direction and moving voltage waves. The frequency determines the cable’s characteristic impedance, while the length has no effect.

The impedance of high-frequency technology is usually 50 ohms. For television and audio technology, it is 75 ohms. The reactance and the ohmic resistance are the two main factors determining the impedance.

Coaxial Cables have two main advantages: high transmission speed and simple connections. SMA connectors and RP SMA connectos are the most common and important types of coaxial connectors.


What are SMA Connectors?



SMA and RP – SMA Connectors

SMA Connectors 

In the 1960s, the SMA connectors became a standard. SMA stands for Sub-Miniature Version A. Both versions of the corresponding connectors have coaxial designs in order to maintain coaxial cable transmission speeds. They are, therefore,  capable of shielding electrical interference and low levels of electromagnetic interference.


RP-SMA Connectors

The Reverse Polarity SMA design is easy to confuse with an SMA connectors. This variant was initially designed to prevent unauthorized connections of stronger antennas. The “reverse polarity” of the RP–SMA refers only to the interface variant and not to the signal polarity.

The RP-SMA connectors also has an inner thread, but it has a cup in the middle of the connector and not the pin. Compatibility with this socket consists of a female thread and a pin. The SMA antenna connection fits mechanically in an RP-SMA socket but not electrically.


Comparison of the two designs

SMA and RP–SMA are standard-threaded antenna connectors for high-frequency applications, from 1 GHz to approximately. 16 GHz. They are used most often in microwave systems such as portable radios and mobile antennas, but they can also be used with WiFi antenna systems.

In the reverse design, the two versions are different. The SMA connectors features a union pin and an inner conductor pin. The socket consists of a male and inner conductor tubes.


Applications of SMA or RP-SMA

An SMA connection’s primary use is in the LTE / GSM / UMTS area as a standard for antennas or devices. RP-SMA is mainly employed for WLAN antennas. An often-used application is to improve reception by moving or extending the feed to a WLAN antenna. There are many connections for SMA due to the different antenna designs and application areas. These connections should be modified if necessary by adapters.

RP-SMA has one advantage over SMA: wear. The signal strength can decrease if the inner conductors are worn out. This is usually due to frequent unscrewing and undressing. It is more difficult to replace the connector on an SMA-built-in socket. An RP-SMA connector is, however, located on the antenna/cable. This means that only the antenna or the cable would need to be replaced in the event of wear.


If you would like to receive a quote for any of custom cables or connectors, please do not hesitate to contact us by sending an email to [email protected] or calling in the USA this phone number (682-325-1944).




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