Mast radiator

<div style="float: right; clear: right; margin-left: 1.4em">thumb|300px|none|The Blosenbergturm in Beromünster, Switzerland - a radiating tower insulated against ground</div>A mast radiator (or 'radiating tower') is a radio mast or tower in which the whole structure itself functions as an antenna. This design is commonly used for transmitting antennas operating at low frequencies, in the VLF, LF and MF ranges, in particular those used for AM broadcasting. The metal mast is electrically connected to the transmitter. Its base is usually mounted on a nonconductive support to insulate it from the ground. A mast radiator is a form of monopole antenna.

Design considerations

Design

Most mast radiators are built as guyed masts insulated from the ground at the base. Steel lattice masts, of triangular cross-section, are the most common type. Square lattice masts and tubular masts are also sometimes used. To ensure that the tower is a continuous conductor, the tower's structural sections are electrically bonded at the joints by short copper jumpers which are soldered to each side.

At its base, the mast is usually mounted on a thick ceramic insulator, which has the compressive strength to support the tower's weight and the dielectric strength to withstand the high RF voltage applied by the transmitter. The RF power to drive the antenna is supplied by an antenna tuner unit, usually housed in a small building called a helix building next to the mast, and...
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