subject: How To Get The Best Signal And Performance From Rf Cables [print this page] RF cables are the same as coaxial cables and they provide certain characteristics for electrical resistance ensuring that the cables match the electronic systems for the largest amount of power transfer with the smallest amount of signal reflection.
RF cables made of a cable that carries two metal leads, one inside the other. The two wires do not carry two different signals; instead, they carry the power and ground for a single signal, with the ground (outside) cable providing limited shielding from radio interference.
Coaxial RF cables are typically manufactured using a copper conductor that is separated by polyethylene from braided pairs, is covered by a PVC jacket to protect the copper wires, and all of these elements share a central axial line.
A method of routing RF cables along low electric field areas of a local coil in a predictable and reliable manner is presented. A conductive ring is introduced into proximity with the coil loops and connected to the ground shield of the RF cables creating a low electric field area. The RF cables are attached to the conductor along the ring to a point where they exit together as a unified cable. The ring, by defining an area of low electromagnetic field, reduces interference on the cables and coupling between loops allowing for a controlled cable layout.
There are two types of RF cables: 75-ohm coaxial and 300-ohm parallel. This second type was used by old terrestrial broadcasting antennas, but even this kind of antenna uses the 75-ohm coaxial cable presently. You can install a 300-ohm cable/connector into a 75-ohm connector by using an adapter.
Since long cables will significantly reduce operating range, especially at UHF, RF cables should be kept as short as practical. The size and type of cable used should be matched to the frequency range and the required cable length. When the cables must be long, a higher-quality cable is required and a larger size with lower losses should be selected. RF cable losses are considerably higher at UHF frequencies as compared to VHF frequencies, and cable length and cable type are much more critical.
The F-type cable is a connector that is used to transmit satellite television or data over cable modems. It is often used with a splitter for use in cable televisions. The Coaxial cable or coax is a connector that is used to transmit signal for home video devices or networking in computers. Long coaxial cables are also used for amateur radios.
To obtain optimum performance from RF cables you should flex and straighten the cables as little and seldom as possible. Make connections carefully to avoid misalignment, connector damage, or inaccurate measurements. Keep the connectors free of dirt and metallic particles by periodic inspection and cleaning.
