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SMA vs 2.9 mm RF Connectors are essential components used in wireless communications, microwave devices, and digital communication systems. While they share many functions and applications, there are considerable differences in their design, performance and application scenarios. What is the difference between SMA and 2.9 mm? This article will elaborate for you.

sma rf connectors

SMA (SubMiniature version a) is a type of 50 ohm coaxial connector with small screw mechanism. Due to the wide bandwidth, high performance, high reliability and long life so it has been popular until today since it was invented in 1960s. We find expression of SMA connector in the RF circuits of microwave equipment and digital communication system to connect RF cables or microstrip lines. SMA connectors are used for the GPS clock interface of wireless devices single board and RF module test port of Base Station.

There are two basic types of SMA connectors: standard SMA and rp-SMA. The traditional SMA uses",The geometry of parts is "External thread + jack" or"Internal thread + pin". SMA connectors are designed for DC to 18 ghz but some precision versions go up to 26.5 ghz, 27 ghz, typically at 50 ohm characteristic impedance. The SMA connector has a low outer diameter of approx 1.24 mm and a high inner diameter of approx 4.13 mm and a high withstand voltage value (usually, 500 vrms).

2.9 mm RF connector

The 2.9 mm RF connector (also called k-connector, or SMK connector) is a high-performance millimeter-wave connector. Introduced in 1983, the connector was created by senior engineer William Old Field from Wiltron, has an inner conductor diameter of 1.27 mm, and is used with SMA and 3.5 mm connectors. 2.9 mm connectors have good electrical properties in the frequency range from DC to 46 ghz (50 ghz for some models). They can also be mechanically mated with SMA and 3.5 mm connectors, which makes them one of the most widely used millimeter wave connectors in the world.

The 2.9 mm connector is of high reliability and low insertion force. 4 slots in the socket ensure good elasticity and the insertion force is only 0.5 lbs (2.224N) , which greatly reduces the wear of the inner conductor and improves the reliability of the connector. Also, the conductor wall thickness of the 2.9 mm connector is not only 4 times thicker than that of the SMA connector, but it has also been proven to be superior, the reliability of the connector is obviously a level up. 2.9 mm connectors can also be available with 50R and 75R impedance and typically rated to withstand 750Vrms.

Common differences between SMA and 2.9 mm RF connectors

Size and construction: while SMA and 2.9 mm connectors are usually the same male and female sizes, the outer conductor dimensions are quite different. The SMA connectors have a relatively large outer and inner diameter, while the outer conductor inner diameter of the 2.9 mm connector is smaller, which affects the frequency range and electrical performance they support directly.

Frequency range: The SMA connectors support a frequency range of DC to 18 ghz (some types up to 26.5ghz or higher), while 2.9 mm connectors are effective from DC to 46 ghz (or 50ghz). The 2.9 mm connector has wider application in millimeter wave communication and test.

Power Handling: the more robust connector design in 2.9 mm connectors generally allows for better power handling than SMA connectors. At higher frequency the 2.9 mm connector exhibits lower insertion loss and better voltage standing wave ratio (VSWR).

The 2.9 mm connector has been engineered with additional mating slots and thickened conductor walls which ensures reliable connections and more durable interconnects. Whereas SMA connectors are also extremely reliable, for long runs and in harsh conditions their performance can slowly degrade over time.

SMA Connector Application Scenario SMA Connector is used extensively in microwave field and test interface of wireless equipment due to its small size, stable connection and high frequency of use. Because of its excellent high-frequency performance and reliability, The 2.9 mm Connector is more suitable for high-end applications such as millimeter-wave Communications, radar systems and high-precision test instruments.

Conclusion SMA and 2.9 mm RF connectors have significant contribution in wireless communications, microwave devices and digital communication systems. Nevertheless, both also have their own strengths and weaknesses regarding size, frequency range, electrical performance, reliability and application scenarios. Thus, it is important to consider the relevant application and performance requirements when selecting the component.