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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.
The operator simply finds on the map the location of the target transmitter or receiver (i.e. the other antenna being communicated with) and uses the map to determine the azimuth angle needed to point the operator's antenna. The operator would use an electric rotator to point the antenna. The map can also be used in one way communication.
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.
The antenna gain, or power gain of an antenna is defined as the ratio of the intensity (power per unit surface area) radiated by the antenna in the direction of its maximum output, at an arbitrary distance, divided by the intensity radiated at the same distance by a hypothetical isotropic antenna which radiates equal power in all directions.
In stellar navigation, the reference direction is that of the North Star, Polaris. In satellite broadcasting, a bearing is the combination of antenna azimuth and elevation required to point (aim) a satellite dish antenna in a given direction. The bearing for geostationary satellites is constant. The bearing for polar-orbiting satellites varies ...
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 ...
This article provides a summary description of many of the different antenna types used for radio receiving or transmitting systems. Different types of antennas are made with properties especially optimized for particular uses, and the electrical design of antennas serves as a way to group them:
Although the radiation of an omnidirectional antenna is symmetrical in azimuthal directions, it may vary in a complicated way with elevation angle, having lobes and nulls at different angles. The most common omnidirectional antenna designs are the monopole antenna , consisting of a vertical rod conductor mounted over a conducting ground plane ...