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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 ...
The outer end of each radial wire, sloping down from the top of the antenna, is connected by an insulator to a supporting rope or cable anchored to the ground; the radial wires can also support the mast as guy wires. The radial wires make the antenna look like the wire frame of a giant umbrella (without the cloth) hence the name.
A dipole can be fed from very near its end (needing to be only about 1 / 20 th of the dipole length from the actual end) but the end impedances are exceedingly high – a few thousands of ohms, depending on the average height of the antenna and thickness of its wire. The end location has an inconveniently high impedance, but it is ...
The upper and lower ends of the conductors are connected at the ends, by wire sections that follow the end dowels. Fed in the middle of the lower conductor, with an impedance in the order of 300 Ω, balanced, through a standard 4:1 balun. This provides an acceptable all-frequency match to commonly available 75 Ω coaxial cable.
The J-pole antenna is an end-fed omnidirectional half-wave antenna that is matched to the feedline by a shorted quarter-wave parallel transmission line stub. [5] [1] [6] For a transmitting antenna to operate efficiently, absorbing all the power provided by its feedline, the antenna must be impedance matched to the line; it must have a resistance equal to the feedline's characteristic impedance.
The antenna feedpoint is usually high in the air (for example, a dipole antenna) or far away (for example, an end-fed random wire antenna). A transmission line, or feedline, must carry the signal between the transmitter and the antenna. The ATU can be placed anywhere along the feedline: at the transmitter, at the antenna, or somewhere in between.
Barr’s term as the Fed’s top banking official was set to expire in July 2026 while his term as governor ends in January 2032. For weeks, Trump has sought to remove Barr from his banking role ...
An automotive wiring diagram, showing useful information such as crimp connection locations and wire colors. These details may not be so easily found on a more schematic drawing. A wiring diagram is a simplified conventional pictorial representation of an electrical circuit. It shows the components of the circuit as simplified shapes, and the ...