The shielding ofRF connectors prevents the radiation and emission of the high frequency and the ultrahigh frequency. The defined characteristic impedance is the prerequisite for broadband, low- attenuation transmission. For this reason, high frequency with frequencies of up to 20 GHz is transmitted via coaxial cable. Waveguides are used for higher frequencies.
To realize the connection between two coaxial cables or the connection of coaxial cables to RF circuits, detachable connection components are required; known as RF connectors.
RF connectors are coaxial in design; they consist of an inner conductor, the dielectric and the outer conductor. In the case of the plug, the inner conductor is a pin; in the case of the socket, the inner conductor is a small tube into which the pin is inserted. The outer conductor is the metallic screw cap or the locking cap, which at the same time shields the plug against interference.
RF connectors differ in size, thickness of the coaxial cable that can be connected, frequency range, RF tightness, impedance and some other parameters.
The development started with the UHF connector and continued with a wide range of variants, such as the well-known BNC connector, the N connector, TNC connector, APC connector and the F connector, and went on to the miniature RF connectors, such as the SMA connector, SMB connector, SMC connector, as well as the subminiature connectors, such as the MC card connector, the U.FL connector and the MMCX connector, which are installed in miniature devices, in PC cards and directly on the boards.
There is a whole range of microwave connectors whose designation refers to the connector diameter, such as the 7-mm connector, 3.5-mm connector, 2.92-mm connector, 1.85-mm connector or the 1-mm connector. These connectors cover the frequency range between 20 GHz and 110 GHz.