天线效率

IEEE Standard for Definitions of Terms for Antennas (IEEE Std 145™-2013 )

antenna efficiency of an aperture-type antenna: For an antenna with a specified planar aperture, the ratioof the maximum effective area of the antenna to the aperture area.

effective area (of an antenna) (in a given direction): In a given direction, the ratio the available powerat the terminals of a receiving antenna to the power flux density of plane wave incident on the antennafrom that direction, the wave being polarization matched to the antenna. See: polarization match.

NOTE 1—If the direction is not specified, the direction of maximum radiation is implied.

NOTE 2—The effective area of an antenna in a given direction is equal to the square the operating wavelength timesits gain in that direction divided by 4π.

NOTE 3—For an active receiving antenna, available power is the active antenna available power. See: active antennaavailable power.

antenna illumination efficiency / aperture illumination efficiency / normalized directivity: The ratio, usually expressed in percent, of the maximumdirectivity of an antenna [aperture] to its standard directivity.

NOTE—For planar apertures, the standard directivity is calculated by using the projected area of the actual antenna in aplane transverse to the direction of its radiation intensity.

standard directivity / referencedirectivity: The maximum directivity from a planar aperture of area A, or from a linesource of length L, when excited with a uniform-amplitude, equiphase distribution.

NOTE 1—For planar apertures in which A >>λ2, the value of the standard directivity is 4πA/λ2, with λ the wavelengthand with radiation confined to a half space.

NOTE 2—For line sources with L >>λ, the value of the standard directivity is 2L/λ.

aperture distribution / aperture illumination: The field over the aperture as described by amplitude, phase, and polarizationdistributions.

radiation efficiency: The ratio of the total power radiated by an antenna to the net power accepted by theantenna from the connected transmitter.

realized radiation efficiency / total radiation efficiency.: The radiation efficiency of an antenna reduced by its impedance mismatchfactor.