Page 246 - Electrical Engineering Dictionary

that received by the antenna placed in the effective radiated power (ERP) the ef-
same field. At a given wavelength, the ef- fective power output from an antenna in a
fective aperture is directly proportional to the specifieddirection, includingtransmitterout-
gain. put power, transmission line loss, and an-
tenna power gain.
effective dielectric constant (1) simple
andsingledielectricconstantusedtodescribe efficiency (1) the ratio of the input power
a complicated configuration of media with a to the output power. It is a figure of merit for
variety of dielectric constants in an equiva- the energy cost effectiveness of a device.
lent model. (2) in antennas, the ratio of the power ra-
diated to the input power. This term is some-
(2) the resulting computational effects 2
times defined with the mismatch loss (1−γ )
of having two dielectric materials in a mi-
included in the total efficiency of the antenna;
crostrip transmission line.
other times, it is omitted from the calculation.
effective isotropic radiated power the efficient estimator an unbiased estimator
product of the total radiated power by the di- which achieves the Cramer-Rao bound. See
rective gain of the antenna. also Cramer-Rao bound.

effective isotropically radiated power EFIE See electric field integral equation.
(EIRP) in antenna theory, the amount of
power needed by an isotropic radiator to pro- EGA See enhanced graphics adaptor.
duce the same radiation intensity at a receiver
as the original antenna in the main beam di- EIA Electronics Industry Association.
rection. EIRP, which is expressed in decibel-
meters or decibel-watts, can be calculated by eigenfunction the name given to an eigen-
multiplying power supplied to an antenna by vector when the eigenvectors arise as solu-
its directive gain in the desired direction. See tions of particular types of integral equation.
also effective radiated power. See also eigensystem, eigenvector.
eigenfunction expansion a method used
effective length the ratio of the volt-
to expand a given field in terms of eigenfunc-
age induced across an antenna terminat-
tions. It is particularly used in modal analysis
ing impedance divided by the incident field
of waveguide discontinuities.
strength.
eigenstate a linear combination of quan-
effective mass an approach whereby a tum mechanical basis states that is constant
particular response is described using clas- in time. A quantum mechanical system start-
sical equations by defining an effective mass ing in an eigenstate will remain unchanged in
whose value differs from the actual mass. For time except for an overall phase. The phase
example, an electron in a lattice responds dif- varies as the product of the eigenvalue and
ferently to applied fields than would a free time. Quantum mechanical eigenstates are
electron or a classical particle. analogous to normal modes of coupled oscil-
lator systems in classical mechanics.
effective permittivity a simple and single
permeabilityconstantusedtodescribeacom- eigensystem a system where the output of
plicated configuration of media with a vari- a system is the input function multiplied by a
ety of permeability constants in an equivalent constant. See alsoeigenfunction, eigenvalue,
model. eigenvector.

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2000 by CRC Press LLC