How to choose RF coaxial connector
As an important part of passive components, RF coaxial connector has good broadband transmission characteristics and a variety of convenient connection modes, so it is widely used in test instruments, weapon systems, communication equipment and other products. As the application of RF coaxial connector almost penetrated into all sectors of the national economy, its reliability has attracted more and more attention. This paper analyzes the failure mode of RF coaxial connector and discusses how to improve its reliability.
Although there are many kinds of RF coaxial connectors, the connection principle is basically the same whether it is threaded connection type such as n-type, SMA, 3.5mm, bayonet connection type such as BNC, C, or push in connection type such as SMB, SSMB, McX. Taking n-type connector as an example, the failure mode and the method of improving reliability are analyzed.
After the n-type connector pair is connected, the contact surfaces (Electrical and mechanical reference surfaces) of the outer conductor of the connector pair are mutually tightened by the pulling force of the thread, so as to achieve small contact resistance (< 5m) Ω)。 The pin part of the inner conductor of the pin is inserted into the hole of the inner conductor of the socket, and the two inner conductors are kept in good electrical contact (contact resistance < 3M) at the mouth of the inner conductor of the socket through the elasticity of the hole wall Ω)。 At this time, the step surface of the inner conductor of the pin and the end surface of the inner conductor of the socket are not tight, but there is a gap of < 0.1mm, which has an important impact on the electrical performance and reliability of the coaxial connector. The ideal connection state of n-type connector pair can be summarized as follows: good contact of outer conductor, good contact of inner conductor, good support of dielectric support for inner conductor, correct transmission of thread tension. Once the above connection state changes, it will lead to the failure of the connector. Next, we will start from these points to analyze the failure principle of the connector, so as to find the correct way to improve the reliability of the connector.