The F connector is an inexpensive, gendered, threaded, compression connector for radio frequency signals. It has good 75 Ωimpedance match for frequencies well over 1 GHz and has usable bandwidth up to several GHz. Connectors mate using a in-32 unified extra fine thread. The female connector has a socket for the center conductor and external threads. The male connector has a center pin, and a captive nut with internal threads. The design allows for low-cost construction, where cables are terminated almost exclusively with male connectors. The coaxial cable center conductor forms the pin, and cable dielectric extends up to the mating face of the connector. Thus, the male connector consists of only a body, which is generally crimped onto or screwed over the cable shielding braid, and a captive nut, neither of which require tight tolerances. Push-on versions are also available. Female connectors are typically used on bulkheads or as couplers, often being secured with the same threads as for the connectors. Thus can be manufactured as a single piece, with center sockets and dielectric, entirely at the factory where tolerances can easily be controlled. This design is subject to the surface properties of the inner conductor and is not corrosion resistant. Hence waterproof versions or enclosures are needed for outside use. Corrosion resistance, reliability of connector electrical conduction and water resistance can be improved by coating all bare copper wires and the connectors themselves with silicone grease.
Weatherproofing
The F connector is not weatherproof. Neither the threads nor the joint between male connector body and captive nut seal. However, male connectors are commonly enhanced with an o-ring inside the captive nut. This seals between the mating faces of both connectors, providing good waterproofing for the center conductor.
Usage
The cable and satellite television entities use compression fittings with F connectors on customer premises. In Europe, block down-converted satellite signals from LNBs and DC power and block signalling from satellite receivers are near exclusively passed through F connectors. F connectors are probably the most suitable for domestic terrestrial, cable, and satellite TV installations where the delivery of very high frequency information is required. Belling-Lee connectors are not well suited for long-haul building delivery of frequencies above 500MHz, because the standard was designed around tube receivers and mediumwave antennas. F connectors require slightly more care to properly install the male connectors to the cable than the Belling-Lee type, with the exception of compression or flex type connections.
Flex F connectors
Push-on F connectors provide poorer shielding against microwave signals of high field strength. This leakage problem is more an artifact of bent or partly broken push on connectors, but is mostly not observed with compression connectors. Nearby television, FM radio, mobile & cordless phones, government radiolocation transmitters can potentially interfere with a CATV or DTH Satellite reception or operation if the Flex connector is poorly installed.
