Search results
Results from the WOW.Com Content Network
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.
The first antenna is the test antenna whose patterns are to be investigated; this antenna is free to point in any direction. The second antenna is a reference antenna, which points rigidly at the first antenna. Each antenna is alternately connected to a transmitter having a particular source impedance, and a receiver having the same input ...
A high-gain antenna (HGA) is a directional antenna with a focused, narrow beam width, permitting more precise targeting of the radio signals. [1] Most commonly referred to during space missions, [2] these antennas are also in use all over Earth, most successfully in flat, open areas where there are no mountains to disrupt radiowaves. [citation ...
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 ...
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 ...
In antenna engineering, sidelobes are the lobes (local maxima) of the far field radiation pattern of an antenna or other radiation source, that are not the main lobe.. The radiation pattern of most antennas shows a pattern of "lobes" at various angles, directions where the radiated signal strength reaches a maximum, separated by "nulls", angles at which the radiated signal strength falls to zero.
For most antennas the boresight is the axis of symmetry of the antenna. For example, for axial-fed dish antennas, the antenna boresight is the axis of symmetry of the parabolic dish, and the antenna radiation pattern (the main lobe) is symmetrical about the boresight axis. Most antennas boresight axis is fixed by their shape and cannot be changed.
The quarter-wave monopole, the most compact resonant antenna, may be the most widely used antenna in the world. The five-eighth wave monopole – length 0.625 λ , or 5 / 8 of a wavelength – is also popular, since at that length monopoles direct the greatest proportion of their radiated power horizontally, hence the best use of ...