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The trideco antenna is a huge specialized umbrella antenna used in a few high power military transmitters at very low frequency (VLF). [ 5 ] [ 6 ] In a conventional umbrella antenna, the use of the sloping guy wires as the capacitive top load has some disadvantages: First, since the umbrella wires must be anchored to the ground, their length is ...
A 20-meter-long T²FD antenna, covering the 5-30 MHz band. The T ilted T erminated F olded D ipole ( T²FD , T2FD , or TTFD ) or B alanced T ermination, F olded D ipole ( BTFD ) - also known as W3HH antenna - is a general-purpose shortwave antenna developed in the late 1940s by the United States Navy .
English: Diagram of a J-pole antenna, a vertical end-fed half-wave omnidirectional transmitting antenna used in the shortwave frequency bands. It consists of a vertical element a half wavelength (/) long, fed in series with a quarter wavelength (/) transmission line stub, with the coaxial cable feedline (F) from the transmitter attached along the stub.
[9] [better source needed] A length of at least 20 metres (66 ft) of 75 Ω (50 Ω) cable is recommended for operation without a balun. [10] [11] A transmatch (antenna tuner) is not required to use this antenna near its nominal design frequency of 14 MHz, and judicious length adjustments can sometimes include one other frequency band. All other ...
A horn antenna has a flaring metal horn attached to a waveguide. It is a simple antenna with moderate gain of 15 to 25 dBi, used for applications such as radar guns, radiometers, and as feed antennas for parabolic dishes. Slot Consists of a waveguide with one or more slots cut in it to emit the microwaves. Linear slot antennas emit narrow fan ...
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.
Due to their omnidirectional radiation pattern, vertical monopole antennas are commonly used in terrestrial radio communication systems in which the direction to the transmitter or receiver is unknown or constantly changing, [7] such as broadcasting, mobile two-way radios, and wireless devices like cellphones and Wi-Fi networks, [8] [4] because they radiate equal radio power in all horizontal ...
Moxon antenna for the 20-meter band.The antenna is the faint rectangle of wires held in tension by the bent X-shaped support frame. Moxon antenna for the 2-meter band. The Moxon antenna or Moxon rectangle is a simple and mechanically rugged two-element parasitic array, single-frequency antenna. [1]