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Diagram showing directivity: the highest power density of this antenna is in the direction of the red lobe In electromagnetics , directivity is a parameter of an antenna or optical system which measures the degree to which the radiation emitted is concentrated in a single direction.
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.
Antenna directivity is the ratio of maximum radiation intensity (power per unit surface) radiated by the antenna in the maximum direction divided by the intensity radiated by a hypothetical isotropic antenna radiating the same total power as that antenna. For example, a hypothetical antenna which had a radiated pattern of a hemisphere (1/2 ...
Three-dimensional antenna radiation patterns. The radial distance from the origin in any direction represents the strength of radiation emitted in that direction. The top shows the directive pattern of a horn antenna, the bottom shows the omnidirectional pattern of a simple vertical dipole antenna.
English: Diagram explaining how the directivity (directive gain) of an antenna is defined. R (grey) is the radiation pattern of a typical directive antenna. It radiates most of its power in a narrow lobe oriented along the z axis.
In antenna theory, an isotropic antenna is a hypothetical antenna radiating the same intensity of radio waves in all directions. [1] It thus is said to have a directivity of 0 dBi (dB relative to isotropic) in all directions. Since it is entirely non-directional, it serves as a hypothetical worst-case against which directional antennas may be ...
The two-element design gives modest directivity (about 2.0 dB) with a null towards the rear of the antenna, yielding a high front-to-back ratio: Gain up to 9.7 dBi can be achieved at 28 MHz. [3] Because the placement and size of the parasitic reflector both depend highly on wavelength, each Moxon antenna functions properly on the frequency band ...
The beam direction (direction of greatest sensitivity) is to the left. A Yagi–Uda antenna , or simply Yagi antenna , is a directional antenna consisting of two or more parallel resonant antenna elements in an end-fire array ; [ 1 ] these elements are most often metal rods (or discs) acting as half-wave dipoles . [ 2 ]