female connector
a connector present-
ing receptacles for the insertion of the corre-
sponding male connector that presents pins.
fenestration
any opening or arrangement
of opening (normally filled with media for
control) for the admission of daylight.
Ferranti, Sebastian Ziani de
(1864–
1930) Born: Liverpool, Lancashire, England
Ferranti is best known for developing sys-
tems of high-voltage AC power systems. The
generating and transmission systems he de-
signed still form the basis for most modern
power systems. As a principal in the London
Electric Supply Corporation, Ltd., Ferranti
demonstrated that high-voltage AC current
could be distributed and then stepped down
for use in a more efficient and economical
system than the smaller DC current systems
then operating. Ferranti invented a number
of other devices and systems as a consultant
and in his own company. He was named pres-
ident of the Institute of Electrical Engineers
in 1911.
ferrite
a term applied to a large group
of ceramic ferromagnetic materials usually
consisting of oxides of magnesium, iron, and
manganese.
Ferrites are characterized by
permeability values in the thousands and are
used for RF transformers and high Q coils.
ferrite beads
small toroids made of fer-
rites which are slipped over a conductor in
order to suppress RF currents. The beads act
as RF chokes at high frequencies.
ferrite core
a magnetic core made up
of ferrite (compressed powdered ferrromag-
netic) material, having high resistivity and
low eddy current loss.
ferrite core memory
See
magnetic core
memory
.
ferrite material
a material that has very
low conductivity (
σ) and very large perme-
ability (
µ). Its properties can be altered when
an external magnetic field is applied. It is
used in ferrite loaded loop antennas, for ex-
ample, to increase the flux through the loop
antenna.
ferroelectric material
a polar dielectric
in which the crystallographic orientation of
the internal dipole moment can be changed
by the application of an electric field.
ferrofluid
iron based solution employed
in voice coil/pole piece gap improving mag-
netic flux and power handling capacity.
ferromagnetic
materials in which inter-
nal magnetic moments spontaneously line up
parallel to each other to form domains, re-
sulting in permeabilities considerably higher
than unity (in practice, 1.1 or more); exam-
ples include iron, nickel, and cobalt.
ferroresonance
a resonant phenomenon
involving inductance that varies with satura-
tion. It can occur in a system through the
interaction of the system capacitance with
the inductance of, for example, that of an
open-circuited transformer. Ferroresonance
resembles, to some extent, the normal reso-
nance that occurs wherever L-C circuits are
encountered. If the capacitance is apprecia-
ble, ferroresonance can be sustaining or re-
sult in a limited over voltage enough to dam-
age the cable or the transformer itself.
ferroresonant transformer
a trans-
former that is designed to operate as a tuned
circuit by resonating at a particular fre-
quency.
Fessenden, Reginald Aubrey
(1866–
1932) Born: East Bolton, Quebec, Canada
Fessenden is best known as a radio pio-
neer who described the principle of ampli-
tude modulation and the heterodyne effect.
Fessenden became the chief scientist at Edi-
son’s laboratory and then spent two years
with Westinghouse. He later held teaching
posts at Purdue University and Western Uni-
versity of Pennsylvania (now the U. of Pitts-
c
2000 by CRC Press LLC