Although k-connector and 2.4mm-connector have their own advantages and disadvantages, from the development trend of national defense and our current application in the United States, 2.92mm-connector is more widely used than 2.4mm-connector. Therefore, we believe that 2.92mm-connector should be the priority development of the MMW coaxial connector series in China. Therefore, we will focus on the characteristics, advantages and disadvantages of the two RF coaxial connectors.

一、 2.4mm connector
      As early as the 1980s, some experts of HP company in the United States put forward a new idea, completely getting rid of the limitations of SMA connector which is widely used at present, and set the following main goals for the newly developed 2.4 connector.
      1. The performance should be better than SMA connector and apc3.5 connector which are widely used at present;
      2. It has the same strict tolerance as apc3.5 connector;
      3  to 50 GHz with high performance interface;
      4. Compared with the existing connector, it is more competitive in price;
      5.There is no high order mode from 5 to 50 GHz;
      6 in metric design.
      7. Good durability, repeatability and damage resistance;
      8 during normal operation, the socket contact shall not be damaged.

二、 Type K RF coaxial connector
      At the same time, William old field, senior engineer of wiltron company, developed a new type of k-connector based on summarizing and overcoming the previous millimeter wave connector. It can be used in the dc-46ghz frequency band, has good electrical performance, and can be compatible with SMA connector which has been widely used now, and it is quickly recognized by many manufacturers, and has become one of the most widely used millimeter wave connectors in the world. It has the following important characteristics:
      1. Low price;
      2. It is compatible with existing SMA and apc-3.5 connectors in terms of electrical and mechanical properties;
      3. High working reliability. Because the K-joint has 4 grooves in the jack and has good elasticity, and the insertion force is only 0.5 pounds (2.224n), the conductor wear in the K-joint can be greatly reduced, while the reliability is increased by about 12 times. At the same time, the wall thickness of the K-joint conductor is 4 times thicker than that of the SMA joint, so the reliability of the K-joint connector is increased by about 30 times than that of the SMA joint;
      4. Assembly technology is similar to SMA joint. Wiltron company also developed K-joint series complete assembly tools, which not only ensures the assembly accuracy of joint, but also makes the assembly of joint easier to complete;
      5. When it is used below 46ghz, it has excellent electrical performance, and when it is used below 18GHz, it is better than SMA connector;
      6. The K-joint can be fully tested with millimeter wave network analyzer from HP and wiltron.

三、 Standard formulation of 2.92mm and 2.4mm small coaxial connectors
      Recently, China has received the draft standards of NBS (National Bureau of standards) and IEC (International Electrotechnical Commission) for 2.92mm and 2.4mm subminiature coaxial connectors. However, according to relevant reports, IEC voted for the standard of K-type coaxial connector proposed by wiatron company as the IEC standard of 2.92mm coaxial connector by a majority of votes. At the same time, desc (national defense electronic equipment supply center) is also making the final work, actively adopting the suggestion of wiltron company, and expanding the standard of K-type coaxial connector to the U.S. military standard Mil-C-39012 of RF coaxial connector.

四、 Comparison of K-type and 2.4mm MMW connectors
      We have introduced the characteristics of K-type and 2.4mm millimeter wave coaxial connectors in detail. It is not difficult to see that the K-type connector has high working frequency (dc-46ghz), good compatibility with SMA and ap3.5 connector, superior performance index, high reliability, and good cost performance (the price of K-type connector in the U.S. market is 1.2-1.5 times that of SMA connector, but only ap3.5 connector A series of advantages, such as 1 / 2 or even 1 / 3 of the price, make it the most widely used in millimeter wave industry in the United States. It is precisely because of the unique performance and excellent economic value of K-type connector. Mpc3 launched by Maury microwave company and wpm-4 launched by Bruno Weinschel company that we investigated belong to this type of connector. According to incomplete statistics, there are at least 10 connectors in the United States at present The company produces k-connector or millimeter wave coaxial component with k-connector, which is more widely used than the 2.4mm connector introduced by HP company.
      Although there are many kinds of millimeter wave connectors in the world, such as 1.9mm, apc3.5, K-type, 2.4mm and few polarity millimeter wave connectors. Among these millimeter wave connectors, although the frequency of 1.9mm connector can reach more than 50GHz, it has not been widely used due to its poor reliability; however, the nonpolar millimeter wave connector has not been widely used because of its small size; apc3.5 is the first practical millimeter wave coaxial connector with excellent electrical performance, which was introduced by HP and Amphenol in the mid-1970s It is widely used, but because it can not work to the whole frequency band of 8mm, and the manufacturing cost is expensive, which limits the extensive application and further development of this connector. Therefore, most microwave engineers expect to be able to produce millimeter wave connectors with performance similar to apc3.5, and the frequency band can cover the whole 8mm frequency band.
      Article link: China security exhibition website http://www.afzhan.com/company/news/detail/78939.html