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The G5RV antenna is a dipole antenna fed indirectly, through a carefully chosen length of 300 Ω or 450 Ω twin lead, which acts as an impedance matching network to connect (through a balun) to a standard 50 Ω coaxial transmission line. The sloper antenna is a slanted vertical dipole antenna attached to the top of a single tower. The element ...
When considering an antenna's directional pattern, gain with respect to a dipole does not imply a comparison of that antenna's gain in each direction to a dipole's gain in that direction. Rather, it is a comparison between the antenna's gain in each direction to the peak gain of the dipole (1.64). In any direction, therefore, such numbers are 2 ...
Louis Varney (G5RV) invented this antenna in 1946. [4] It is very popular in the United States. [5] The antenna can be erected as horizontal dipole, as sloper, or an inverted-V antenna. With a transmatch, (antenna tuner) it can operate on all HF amateur radio bands (3.5–30 MHz). [5] [6]
An antenna designer must take into account the application for the antenna when determining the gain. High-gain antennas have the advantage of longer range and better signal quality, but must be aimed carefully in a particular direction. Low-gain antennas have shorter range, but the orientation of the antenna is inconsequential.
Since electromagnetic radiation is dipole radiation, it is not possible to build an antenna that radiates coherently equally in all directions, although such a hypothetical isotropic antenna is used as a reference to calculate antenna gain. The simplest antennas, monopole and dipole antennas, consist of one or two straight metal rods along a ...
A directive antenna with moderate gain of about 8 dBi often used at UHF frequencies. Consists of a dipole mounted in front of two reflective metal screens joined at an angle, usually 90°. Used as a rooftop UHF television antenna and for point-to-point data links. Parabolic The most widely used high gain antenna at microwave frequencies and above.
Patch antenna gain pattern. A directional antenna or beam antenna is an antenna which radiates or receives greater radio wave power in specific directions. Directional antennas can radiate radio waves in beams, when greater concentration of radiation in a certain direction is desired, or in receiving antennas receive radio waves from one specific direction only.
The horizontal gain continues to increase up to a maximum of about 6.6 dBi at a length of five-eighths wavelength 5 / 8 λ so this is a popular length for ground wave antennas and terrestrial communication antennas, for frequencies where a larger antenna size is feasible. The input impedance drops to about 40 Ohms at that length.