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A mast radiator or mast antenna is a radio tower or mast in which the whole structure is an antenna. Mast antennas are the transmitting antennas typical for long or medium wave broadcasting. Structurally, the only difference is that some mast radiators require the mast base to be insulated from the ground.
Counterpoises are typically used in antenna systems for radio transmitters where a good earth ground connection cannot be constructed.. Monopole antennas used at low frequencies, below 3 MHz, such as the mast radiator antennas used for AM broadcasting, require the radio transmitter to be electrically connected to the Earth under the antenna; this is called a ground (or earth).
Often random wire antennas are also (inaccurately) referred to as long-wire antennas.There is no accepted minimum size, but actual long-wire antennas must be greater than at least a quarter-wavelength ( 1 / 4 λ) or perhaps greater than a half ( 1 / 2 λ) at the frequency the long wire antenna is used for, and even a half-wave may only be considered "long-ish" rather than "truly ...
If used for transmitting, the resistor makes traveling-wave antennas inefficient, since the resistor absorbs any radio wave after the wave has made a single pass through the antenna wire, as opposed to a resonant antenna in which radio waves cycle back-and-forth several times, giving the signal multiple opportunities to radate.
For example, a dipole antenna for the 80 meter band requires a ground length of about 140 feet (43 m) from end to end. An inverted vee with a 40-foot (12 m) apex elevation requires only 115 feet (35 m). For radio amateurs living on small parcels of property, such savings can make it possible to use the lower frequency amateur bands.
The folded unipole antenna was first devised for broadcast use by John H. Mullaney, an American radio broadcast pioneer, and consulting engineer. [2] It was designed to solve some difficult problems with existing medium wave (MW), frequency modulation (FM), and amplitude modulation (AM) broadcast antenna installations.
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