Radio antenna

       January 1, 0000    1604

 

The antenna is an arrangement of aerial electrical conductors designed to transmit or receive radio waves that is a class of electromagnetic waves. In other terms, antennas mainly convert radio frequency electrical currents into electromagnetic waves. Antennas are used in systems such as radio and television broadcasting point-to-point radio communication, radar and space exploration too. Antennas generally work in air or outer space but can also be operated under water or even through soil and rock at certain frequencies for small distances. There are several variations of antennas that have a variety of configurations. These configurations include space or medium that tends to confine the energy within particular restrictions along a predetermined path known as restricted space, such as wave guides, hollow resonators and conductive wires.
Common models of radio antenna:

1. The isotropic radiator is an entirely theoretical antenna that radiates evenly in all directions. It is measured to be a point in space with no magnitude and no mass. This antenna cannot actually exist but is useful as a theoretical model for comparison with all other antennas.
2. The dipole antenna is basically two wires pointed in opposite directions given either horizontally or vertically with one end of each wire connected to the radio and the other end hanging open in space. Since this is the simplest realistic antenna, it is also used as reference model for other antennas like gain with respect to a dipole is labeled as dBd.
3. The Yagi-Uda antenna is a directional dissimilarity of the dipole with parasitic elements supplementary with functionality similar to adding a reflector and lenses to focus a filament light bulb.
4. Loop antennas have a nonstop conducting path leading from one conductor of a two-wire transmission line to the other conductor. Symmetric loop antennas have a plane of symmetry running along the feed and through the loop. Planar loop antennas lie in a single plane that also contains the conductors of the feed. Three-dimensional loop antennas have wire that runs in all of the x, y, and z directions. By definition they are not planar.

Radiation pattern:
The radiation pattern is a graphical representation of the virtual field strength transmitted from the antenna. As antennas radiate in space often numerous curves are necessary to describe the antenna. If the radiation of the antenna is regular about an exclusive graph is sufficient. Each antenna user has different standards as well as plotting formats. Each format has its own pluses and minuses.
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