Some Common types of RF Connectors

Some Common types of RF Connectors

• 1. BNC

The BNC connector is perhaps one of the most widely used connectors in the test and measurement field. It was developed by Bell Labs in
the early 1950s and is typically used for low power interconnections on RF test equipment such as audio and signal generators, oscilloscopes
and amplifiers. The inexpensive BNC utilizes a bayonet retention collar to provide quick mate/de-mate action and also serves to prevent
accidental disconnection. The BNC connector is typically designed to provide a characteristic impedance of 50 or 75 ohms, depending on the
application. BNC connectors are generally rated for use in the DC – 4 GHz frequency range; however, they are rarely used above 500 MHz. While they are capable of handling 80 – 100 Watts average power up to 1 GHz, they typically do not have a maximum power rating. They do however carry a maximum voltage rating of about 500 V.

• 2. TNC

The TNC connector is merely a threaded-version of a BNC connector. It provides a more secure connection and thus reduces vibration
issues that can be found with the BNC. The TNC will operate at higher frequencies than the BNC and there are also high power TNC versions
available.

• 3. SMA

The Sub-miniature Type A connector was developed in the 1960s and has proven to be a very popular choice in low power, high frequency
applications. It was originally intended for use on 141 type semi-rigid coaxial cable, where the center conductor served as the center pin.
Its use was later expanded to flexible cables with soldered on center pins. It consists of an inner contact ring and a hexagonal clamping nut
attached via a snap ring. Special wrenches are used to achieve the correct torque; typically 5 lb-inches. There are different versions available
such as high frequency, self-locking and precision. Commonly used as interconnects on RF boards, microwave filters, and attenuators, the SMA will operate up to 18 GHz. Precision versions extend the upper frequency limit to 26.5 GHz. Although the SMA will mate to the 2.92mm/’K’, 3.5mm, and APC-3.5 connectors, it is not recommended as slight dimensional differences may result in connector damage.

• 4. 3.5mm

The 3.5mm connector is a precision connector primarily developed at Hewlett Packard (now Keysight Technologies). It is similar in design to the  SMA but employs an air dielectric for higher performance. These connectors perform well to 34 GHz, but typically are used to 26.5
GHz. Since the 3.5mm is a precision connector, it is more expensive than similar designs and is thus often found in calibration kits and metrology applications as opposed to common test and production applications.

• 5. 2.4mm

Developed in the mid 1980s by Hewlett Packard (now Keysight Technologies), this 50 GHz connector employs a 4.7mm outer conductor
arranged around a 2.4mm center conductor. The 2.4mm is available in three grades; general purpose, instrument and metrology. Since these
connectors are not directly compatible with the SMA family, precision adapters are required to mate a 2.4mm connector to an SMA.

• 6. 2.92mm (K type) 

This connector was designed and developed by Wiltron (now Anritsu Corporation). Performance with this connector is comparable to the
2.4mm, although the maximum frequency is limited to 40 GHz. The “K type” designator is derived from its ability to cover all the K-band
frequencies.

• 7. N Type

This is one of the most common RF connectors in use around the world today. This high-performance connector was designed by Bell Labs in the 1940s with a threaded coupling interface and internal gasket to keep out the elements. The N connector is rugged, relatively inexpensive and the standard version is capable of mode-free operation to 11 GHz. Precision versions push the upper frequency limit to 18 GHz. Commonly found on instruments such as amplifiers, directional couplers, power meters, and coaxial attenuators, this threaded, durable connector provides a very secure connection. There are both 50 and 75 ohm versions available; the latter commonly used in the CATV industry.

• 8. C Type

The C connector was designed by Amphenol to handle high power applications as well as provide quick mate/de-mate action. It uses a
dual-stud bayonet retention collar similar in design to the BNC. The popularity of the C connector has diminished over the years but is
still available. The 7-16 DIN has been used as a replacement in many cases due to its similar frequency and power capabilities. There are 75
ohm versions available as well as an “SC” version which incorporates a threaded collar for a more secure connection.

• 9. 7-16 DIN

This is a more recent connector in the United States, compared to the other connectors previously mentioned. The 7-16 DIN was developed by the Deutsches Institut fur Normung, (translation: the German National Standards Organization); hence the “DIN” designation. The numerical part of its name refers to the size of the inner and outer conductors; “7” for the inner conductor OD in mm, and “16” for the outer conductor ID in millimeters. The 7-16 uses an M29 x 1.5 threaded coupling nut. The 7-16 DIN connector was designed with low inter-modulation in mind for communications applications. Other common applications include antennas, base station connections, RF cables, SATCOM and lightning protection systems.