F Type Cables
F type cables and connectors are used in everyday settings throughout the world. The cables are basic coaxial cables that are used for cable and terrestrial television transmission.
The History of F type Cables
F type cables are a modified form of simple RF (radio frequency) connectors. RF connector cables are designed to work as electrical connectors. These connectors are fashioned to work with radio frequencies over a range of different MHz and are made from typical coaxial cables.
The difference between coaxial cables and other cables is that the inner conductor and the outer metallic sheet are aligned in a geometric axis. This insures efficient transfer of signals from one end of the cable to the other end. The dimensions of coaxial cables are controlled to deliver precise conductor spacing that allows the cable to perform as a radio frequency transmitter while carrying low radio frequency signals.
The coaxial cables were first invented during the late 19th century. By the mid-20th century, electronic companies were looking for cables that could be easily used with television sets that were developed for household use. By the 1970’s, F type cables had replaced UHF and twin-lead cables and were used in households for connecting all VHF television antennas.
F Type Cable Structure
The cable is constructed just like any other coaxial cable. The electrical signal is carried through the inner conductor. The inner conductor is made from either a solid copper wire or a bunch of strands of copper. This dielectric conductor is covered with an insulated layer. The layer is covered with a mesh of metallic braid (also known as the shield) that is again covered with a plastic covering or jacket.
Current is carried by the central conductor after a voltage is applied. The shield carries no current and it usually has a ground potential. By having an insulator around the central conductor or dielectric, it helps in preventing loss of any magnetic or electric fields from the cable. On the other hand, it is just as difficult for magnetic and electric fields to enter the wire from any outside source. It is for this reason that these cables are ideal for carrying all types of sensitive signals that cannot tolerate any interference from any outside source or signals that should not have any affects to other outside signals.
The resistance of the cable is determined through the central conductor, the shield and the inner insulator. Since F type cables mostly use a solid central dielectric, the cables are low cost. The cables also have an added advantage of providing a resistance of 75 ohms along with a bandwidth that can easily match the impedance from a few MHZ to 1 GHz and can easily go up to several GHz.
F Type Cable Components
As already established, the F type cables are constructed using various coaxial cable components. The components join together and are influential on the performance, strength, size, flexibility, and capability to handle power and cost of the cable being produced and purchased. At times, the inner conductor is covered with silver plating but mostly the central conductor is made of copper.
The dielectric insulator can be of different types. It can be the basic solid plastic covering, a foam covering or it can be spaces filled with air all around the central conductor. The material used for insulators helps a lot with conducting current properly. For this reason, it is important that the type of insulator used is based on Teflon or polyethylene. For air spaced insulators, air or some form of non conducting gas is used. This insulator is usually covered with a braided copper wire that forms the shield. Since there are gaps in the braided wire, the shield is made more efficient by adding another layer of braided copper wire. This can be altered with a foil shield that engulfs the entire braided copper wire.
How F Type Cables are Used
The solid central conductor makes this type of coaxial cable not only low cost, but also helps in its use on a wide range. Since most cables have a male connector attached to them, it is important to make sure that the inner conductor is waterproof and is not easily corroded. For this reason, waterproof F type cables are used outdoors for aerials and all such connections. The body of the connector is usually screwed or crimped on the exposed part of the outer shield. Over the years, industry standards have evolved and cables use compression setting more often.
Most male type connectors have a threaded connecting ring that match with the cable. These connectors can also use push on connectors. However, these connectors do not provide efficient shielding when the signals are airborne making the resulting video to either have some signals missing or become distorted.
The use of F type cables tended in the television and video industry after it showed significantly better quality compared with Belling-Lee connectors. It is now used for all cable, satellite TV installations and domestic terrestrial transmissions. Though it requires slightly more attention to install the connector to the cable, it is not impossible to do it without any professional help.
F type cable connectors are placed to maintain the quality of the signal that the cable is carrying. It is important that since the signals that are in the cable are protected, the signals that are in the connector should also be protected until and unless the signals are delivered to the receiving device (usually a television set). Compared with a female connector type, a male connector requires slightly more care for installation.
The cable size and quality of connector are very important when it comes to buying an F type cable for common use. Signal splitters are also used for splitting different television or video signals that are to be received by more than one plug. These F type cables are used widely for analog and digital signals for cable television and internet. These cables come in varying sizes and can range from as small at 3 feet to as large as 1000 feet.