# Main lobe

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Main lobe
A 'polar' antenna radiation diagram. The radial distance from the center represents signal strength.

The main lobe, or main beam, of an antenna radiation pattern is the lobe containing the maximum power. This is the lobe that exhibits the greatest field strength.

The radiation pattern of most antennas shows a pattern of "lobes" at various angles, directions where the radiated signal strength reaches a maximum, separated by "nulls", angles at which the radiation falls to zero. In a directional antenna in which the objective is to emit the radio waves in one direction, the lobe in that direction is designed to be bigger than the others; this is the main lobe. The other lobes are called "sidelobes", and usually represent unwanted radiation in undesired directions. The sidelobe in the opposite direction from the main lobe is called the "backlobe".

The radiation pattern referred to above is usually the horizontal radiation pattern, which is plotted as a function of azimuth about the antenna, although the vertical radiation pattern may also have a main lobe. The beamwidth of the antenna is the width of the main lobe, usually specified by the half power beam width, the angle encompassed between the points on the side of the lobe where the power has fallen to half (-3 dB) of its maximum value.

This article incorporates public domain material from the General Services Administration document "Federal Standard 1037C" (in support of MIL-STD-188).

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• main lobe — pagrindinis lapelis statusas T sritis radioelektronika atitikmenys: angl. main lobe; major lobe; principal lobe vok. Hauptkeule, f; Hauptzipfel, m rus. главный лепесток, m; основной лепесток, m pranc. lobe principal, m …   Radioelektronikos terminų žodynas

• lobe principal — pagrindinis lapelis statusas T sritis radioelektronika atitikmenys: angl. main lobe; major lobe; principal lobe vok. Hauptkeule, f; Hauptzipfel, m rus. главный лепесток, m; основной лепесток, m pranc. lobe principal, m …   Radioelektronikos terminų žodynas

• lobe — [lōb] n. [Fr < LL lobus < Gr lobos < IE base * lob , var. of * leb , to hang down > LAP1, SLEEP] a rounded projecting part; specif., a) the fleshy lower part of the human ear b) any of the main divisions of an organ separated by… …   English World dictionary

• lobe-foot — lōbeˈ foot noun A phalarope • • • Main Entry: ↑lobe …   Useful english dictionary

• lobe-footed — lōbeˈ footˈed or lōˈbiped adjective Having lobate feet, ie with lobes along the sides of the toes, as a coot does • • • Main Entry: ↑lobe …   Useful english dictionary

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• lobe — A curve representing the relative signal strength plotted against the position of the aerial with respect to a target. four, two at an angle of 7° from the main beam and two at angle of 90°. Side lobes may cause false weak echoes. An antenna… …   Aviation dictionary

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• Side lobe — In antenna engineering, side lobes are the lobes of the far field radiation pattern that are not the main beam, where the terms beam and lobe are synonyms. An antenna radiation pattern is more commonly called a beam pattern. The power density in… …   Wikipedia

• major lobe — pagrindinis lapelis statusas T sritis radioelektronika atitikmenys: angl. main lobe; major lobe; principal lobe vok. Hauptkeule, f; Hauptzipfel, m rus. главный лепесток, m; основной лепесток, m pranc. lobe principal, m …   Radioelektronikos terminų žodynas