Radio frequency power transmission
Encyclopedia
Transmitter
In electronics and telecommunications a transmitter or radio transmitter is an electronic device which, with the aid of an antenna, produces radio waves. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating...
to an antenna
Antenna (radio)
An antenna is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver...
. When the antenna is not situated close to the transmitter, special transmission line
Transmission line
In communications and electronic engineering, a transmission line is a specialized cable designed to carry alternating current of radio frequency, that is, currents with a frequency high enough that its wave nature must be taken into account...
s are required.
The most common type of transmission line for this purpose is large-diameter coaxial cable
Coaxial cable
Coaxial cable, or coax, has an inner conductor surrounded by a flexible, tubular insulating layer, surrounded by a tubular conducting shield. The term coaxial comes from the inner conductor and the outer shield sharing the same geometric axis...
. At high-power transmitters, cage lines are used. Cage lines are a kind of overhead line similar in construction to coaxial cables. The interior conductor is held by insulators mounted on a circular device in the middle. On the circular device, there are wires for the other pole of the line.
Cage lines are used at high-power transmitters in Europe, like longwave transmitter Topolna
Topolna transmitter
The Topolna transmitter is the central longwave broadcasting facility of the Czech Republic situated westward of the village Topolná at the Morava River....
, longwave-transmitter Solec Kujawski
Longwave-transmitter Solec Kujawski
The Longwave transmitter Solec Kujawski is a longwave broadcasting facility of the Polish broadcasting company for the 225 kHz frequency. Its construction was necessary after the collapse of the Warsaw radio mast on August 8, 1991 and the resistance of the local population to its reconstruction.The...
and some other high-power transmitters for long-, medium- and shortwave.
For UHF and VHF, Goubou line
Goubou line
A Goubau line , or G-line for short, is a single wire transmission line intended for use at UHF and microwave wavelengths.-Description:...
s are sometimes used. They consist of an insulated single wire mounted on insulators. On a Goubou line, the wave travels as longitudinal currents surrounded by transverse EM fields. For microwave
Microwave
Microwaves, a subset of radio waves, have wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz and 300 GHz. This broad definition includes both UHF and EHF , and various sources use different boundaries...
s, waveguide
Waveguide
A waveguide is a structure which guides waves, such as electromagnetic waves or sound waves. There are different types of waveguides for each type of wave...
s are used.
