what are field zones in antenna?
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The fields surrounding an antenna are divided into 3 primary regions: Reactive Near Field. Radiating Near Field or Fresnel Region. Far Field or Fraunhofer Region. The far field region is the most important, as this determines the antenna's radiation pattern.
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In EM waves the phase difference between electric and magnetic fields is 180 degree.
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Typically a cell tower is located at the edge of one or more cells and covers multiple cells using directional antennas. ... The type of antenna used for cellular base stations (vertical white rectangles in pictures), called a sector antenna, usually consists of a vertical collinear array of dipoles.
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Assuming no obstructions, a single CB antenna has a uniform, circular signal pattern. It can send and receive in all directions equally, as illustrated by the picture below. Dual antenna installations don't have the same signal pattern.
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The frequencies of radar sets today range from about 5 megahertz to about 130 gigahertz (130,000,000,000 oscillations per second!). However, certain frequencies are also preferred for certain radar applications. Very long-range radar systems usually operate at lower frequencies below and including the D-band.
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This range is known as the electromagnetic spectrum. The EM spectrum is generally divided into seven regions, in order of decreasing wavelength and increasing energy and frequency. The common designations are: radio waves, microwaves, infrared (IR), visible light, ultraviolet (UV), X-rays and gamma rays.
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Non-radiative 'near-field' behaviors dominate close to the antenna or scattering object, while electromagnetic radiation 'far-field' behaviors dominate at greater distances.
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['Microwaves.', 'X-ray.', 'Radio waves.', 'Ultraviolet waves.']
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Uniform Linear Array. Estimation, Signal, Antenna. ULA. Upper Limb Absence. Rehabilitation.
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['The microwave region of the electromagnetic (EM) spectrum is generally considered to overlap with the highest frequency (shortest wavelength ) radio waves.', 'The prefix “micro-” in “microwave” is not meant to suggest a wavelength in the micrometer range.']
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Antenna gain: is the relative measurement of an antenna's ability to direct or concentrate the radiated signal emitting from it. Gain is measured in Dbi (decibels relative to an isotropic radiator) or Dbd (decibels relative to a dipole radiator). ... A change in power by a factor of 10 is a 10 dB change in level.
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Radio waves are at the lowest range of the EM spectrum, with frequencies of up to about 30 billion hertz, or 30 gigahertz (GHz), and wavelengths greater than about 10 millimeters (0.4 inches). Radio is used primarily for communications including voice, data and entertainment media.
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Broadcast Frequency and Antenna Design UHF and VHF radio frequencies operate at different wavelengths. A VHF signal sends relatively large radio waves, while UHF signals are sent on smaller waves that arrive closer together. ... The elements or prongs of your antenna are directly related to the length of the radio wave.
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Radars usually operate at radio frequencies (RF) between 300 MHz and 15 GHz. They generate EMFs that are called RF fields.
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There are two main types of antennas: digital and analogue. ... The main difference between them is that analogue antennas were designed to pick up analogue signals, whereas digital antennas are designed to receive and interpret digital signals.
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At radio and microwave frequencies, electric and magnetic fields are considered together as the two components of an electromagnetic wave. Power density, measured in watts per square metre (W/m2), describes the intensity of these fields.
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The first Fresnel zone is an elliptical area along the length of a signal path that should be kept free of obstructions. When an object extends into a significant portion of the Fresnel zone, the signal can be diffracted and distorted.