A radio frequency connector is a device that transmits radio frequency (RF) signals, which can pass signals into or out of subsystem modules and circuits. The equipment is usually connected to an external antenna via a cable or directly to realize the interconnection of the subsystems. RF connectors can also be used for board-to-board interconnection. Typical applications include mobile radios, cell phones and high-performance data interfaces.
Connectors come in many types, orientations, and impedance characteristics with frequency and target application requirements. The installation can be surface mount on the circuit board, or through holes instead. It is also possible to provide a connector installed (baffle plate) on the chassis connected to the PCB via a cable. Different types of connectors are connected with radio frequency adapters for cable conversion and conversion between male and female interfaces.
The main electrical properties of RF connectors include the following aspects: characteristic impedance of the connector (also related to the cable connecting the connector), return loss (matching-or signal reflection) and insertion loss (signal attenuation). These aspects must be carefully considered in the radio frequency system, because the loss of the signal can lead to the reduction of receiver sensitivity or transmission output power. When using RF connectors for high-frequency data transmission cables (such as UHD SDI video feeds), the quality of the connectors can affect the length of the connecting cable that can be used between devices.
The typical impedance values of the RF interconnection are 50 ohms and 75 ohms. Collectively referred to as connector male plug and female socket. Various connectors use different mechanisms together. The BNC connector is a bayonet locking mechanism. N-type and TNC have a sheath, and the sheath is threaded on the connector for firm connection. SMA and SMB are just examples of threaded connections. Some (such as F connectors) use the center core conductor of the cable to connect to the jack instead of to the pin. Some miniature board mount or ultra-thin cable connectors use gouged connections that are held together by contact pressure. They are intended to be used internally in product enclosures, but can also be seen on equipment. The UMC-MMXC RF connector is just one example.
Although connectors are usually used in a designated operating frequency band, they are also used in applications that completely exceed their operating frequency band, but the overall circuit design will adjust their loss. UHD video feed is just one example. Generally, the 75-ohm BNC connector with the highest frequency specification of 1.5GHz is more common for 6Gbit/s serial data (loss in the range of several decibels, poor matching) systems. The video system adjusts it in the same way as the loss of the cable itself, that is, equalizing the signal received by the receiver.
Other important features to consider when selecting a connector are the insertion force requirements, the connection tools used, and the number of insertions that the connector can reliably support without degrading performance. Many connectors must deal with extreme temperatures and environmental factors and temperature cycling-it is advantageous to consider the environmental requirements of the product in the decision-making process.
