SMA connector, 3.5mm, 2.92mm, 2.4mm difference

Engineers in the test and measurement industry often struggle with a problem. The interface on the instrument can connect to the probe or the instrument. This is the SMA interface or the 2.92 interface. Today, Xiaobian uses the network source to sort out the differences between the four connector interfaces SMA, 3.5mm, 2.92mm, and 2.4mm.

The SMA RF coaxial connector was designed by Bendix and Omni-Spectra as an OSM connector in the late 1950s and was one of the most commonly used RF/microwave connectors at the time. Originally, HYEC.com/en/SMA-Connector.html target='_blank'>SMA connectors were designed for 0.141" semi-rigid coaxial cables, as well as precision connectors for microwave applications in the military industry, filled with Teflon media. At the time, due to the small size of the HYEC.com/en/SMA-Connector.html target='_blank'>SMA connectors, It can work at a higher frequency (with a frequency range of DC to 18 GHz with a semi-hard cable; DC to 12.4 GHz when a flexible cable is mated), and it has quickly gained popularity. Even the millimeter-wave connectors that were later developed (such as 3.5mm, 2.92mm) also considers the problem of compatibility with its machinery.

3.5mm connector:

The 3.5mm connector is a connector with an outer conductor diameter of 3.5mm, a characteristic impedance of 50Ω, and a connection mechanism of 1/4-36UNS-2 inch thread. In the mid-1970s, the United States Hewlett-Packard and Amphenol (mainly developed by HP, the early production at Amphenol) introduced a 3.5mm connector, operating at 33GHz, which is the earliest available An RF coaxial connector in the millimeter band. One significant difference from SMA connectors (including Southwest Microwave's "Super SMA") is that 3.5mm uses air media.

The outer conductor of the 3.5mm connector is thicker than the SMA connector and has better mechanical strength than the SMA connector. Therefore, not only the electrical performance is better than the SMA connector, but also the mechanical durability and performance repeatability are higher than the SMA connector, so it is more suitable for the test industry.

2.92mm connector:

2.92mm connector (some manufacturers call this connector 2.9mm or K-type connector, some manufacturers call it SMK, KMC, WMP4 connector, etc.) is the outer conductor inner diameter is 2.92mm, the characteristic impedance is 50Ω, the connection The mechanism is a 1/4-36 UNS-2 inch threaded RF coaxial connector. Its structure is similar to that of a 3.5mm connector, but it is smaller.

In 1983, Wiltron's William.Old.Field senior engineer developed a new 2.92mm/K connector based on summarizing and overcoming the previously introduced millimeter-wave connector (K-type connector is a trademark of Wiltron Corporation). The inner conductor has a diameter of 1.27mm and can be inserted into the SMA and 3.5 connectors. 2.92mm connector has good electrical performance in the range of DC ~ 46GHz, and can be mechanically compatible with SMA connector and 3.5mm connector. It is quickly recognized by many manufacturers and becomes the most widely used millimeter wave in the world. One of the connectors.

2.4mm connector:

The outer conductor has an inner diameter of 2.4 mm and a 50 ohm impedance connector. The mechanical compatibility with the 2.4 mm connector is a 1.85 mm connector. The outer conductor has an inner diameter of 1.85 mm and both have an impedance of 50 ohms. They have a small internal diameter and therefore a higher operating frequency with nominal frequencies of 50 GHz and 67 GHz, respectively. Keep in mind that they must not be connected to a 2.92mm, 3.5mm or SMA connector, as a result of connector damage!

to sum up:

With the rapid development of millimeter wave technology and high-speed communication technology, 2.92mm, 2.4mm and 1.85mm connectors are more and more widely used in military, aerospace, optoelectronic and other fields, and the more combined with GPPO, GPO and other connectors. The more you come.