Terms starting with ‘A’
- Acceptance Pattern
- Of an antenna, for a given plane, a distribution plot of the off-axis power relative to the on-axis power as a function of angle or position. Note: The acceptance pattern is the equivalent of a horizontal or vertical antenna pattern. Of an optical…
- Access Point
- A device that transports data between a wireless network and a wired network (infrastructure).
- Adaptive (Smart) Antenna
- An antenna system having circuit elements associated with its radiating elements such that one or more of the antenna properties are controlled by the received signal.
- An electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver. In transmission, a radio transmitter applies an oscillating radio frequency electric current to…
- Antenna Directivity
- The directivity of a wireless antenna is given by the ratio of the maximum radiation intensity (power per unit solid angle) to the average radiation intensity (averaged over a sphere). The directivity of any source, other than isotropic, is always…
- Antenna Efficiency
- The total antenna efficiency accounts for the following losses: (1) reflection because of mismatch between the feeding transmission line and the antenna and (2) antenna conductor and dielectric losses.
- Antenna Gain
- The maximum gain of a wireless antenna is simply defined as the product of the directivity by efficiency. If the efficiency is not 100 percent, the antenna gain is less than the directivity. When the reference is a lossless isotropic antenna, the…
- Antenna Polarization
- In a specified direction from a wireless antenna and at a point in its far field, is the polarization of the (locally) plane wave which is used to represent the radiated wave at that point. At any point in the far-field of an antenna the radiated…
- Aperiodic Antenna
- Antenna designed to have constant impedance over a wide range of frequencies because of the suppression of reflections within the antenna system. Includes terminated wave and rhombic antennas.
- Aperture (Antenna)
- A measure of how effective an antenna is at receiving the power of radiowaves. The aperture is defined as the area, oriented perpendicular to the direction of an incoming radio wave, which would intercept the same amount of power from that wave as…
- Aperture Illumination
- The ratio of the directivity of the AUT compared to the directivity of a uniformly illuminated ideal antenna of the same aperture size.
- Aperture-to-medium Coupling Loss
- The difference between the theoretical gain of a very large antenna, such as the antennas in beyond-the-horizon microwave links, and the gain that can be realized in practice.
- The loss in power of electromagnetic signals between transmission and reception points.
- Horizontal direction expressed as the angular distance between the direction of a fixed point (as the observer´s heading) and the direction of the object.