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High-gain antennas have the advantage of longer range and better signal quality, but must be aimed carefully at the other antenna. An example of a high-gain antenna is a parabolic dish such as a satellite television antenna. Low-gain antennas have shorter range, but the orientation of the antenna is relatively unimportant.
It may be said that radio interference and its correction arose with the first spark-gap experiment of Marconi in the late 1800s. [3] As radio communications developed in the first half of the 20th century, interference between broadcast radio signals began to occur and an international regulatory framework was set up to ensure interference-free communications.
Radio-frequency (RF) engineering is a subset of electrical engineering involving the application of transmission line, waveguide, antenna, radar, and electromagnetic field principles to the design and application of devices that produce or use signals within the radio band, the frequency range of about 20 kHz up to 300 GHz. [1] [2] [3]
For example, a Yagi–Uda antenna is constructed from several dipoles arranged at precise intervals to create greater energy focusing (directivity) than a simple dipole. Since it is constructed from dipoles, often its antenna gain is expressed in dB d, but listed only as dB. This ambiguity is undesirable with respect to engineering specifications.
An antenna may have more than one driven element, although the most common multielement antenna, the Yagi, usually has only one. For example, transmitting antennas for AM radio stations often consist of several mast radiators , each of which functions as a half-wave monopole driven element, to create a particular radiation pattern .
This article provides a summary description of many of the different antenna types used for radio receiving or transmitting systems. This summary article collects groups of antennas based on their electrical operation. The classification and sub-classifications below follow those typically used in most antenna engineering textbooks. [1] [2] [3 ...
Stubs are commonly used in antenna impedance matching circuits, frequency selective filters, and resonant circuits for UHF electronic oscillators and RF amplifiers. Stubs can be constructed with any type of transmission line: parallel conductor line (where they are called Lecher lines), coaxial cable, stripline, waveguide, and dielectric waveguide.
A microwave antenna is a physical transmission device used to broadcast microwave transmissions between two or more locations. [1] In addition to broadcasting, antennas are also used in radar , radio astronomy and electronic warfare .