18WuD2x

flat top • flight telerobotic servicer 289
flat top 1. The horizontal radiating portion of an
antenna. 2. See FLAT-TOP ANTENNA. 3. Of an
amplifier, to distort by clipping of the positive
half-cycles.
flat-top antenna An antenna having a horizontal
wire or wires at the top to lower the resonant frequency
and increase the bandwidth.
flat-top beam A bidirectional, end-fire antenna
consisting of two close-spaced dipoles center-fed
out of phase. Also see KRAUS ANTENNA.
flat-topping The positive-peak clipping of a modulation
envelope that occurs when an amplifier is
overdriven or when a signal is overmodulated.
This is in contrast to deliberate clipping. Flattopping
results in “splatter” and is, therefore, an
undesirable characteristic in an amplitudemodulated
signal.
flat-top response The ability to uniformly transmit
frequencies in a given band.
flat transmission line 1. A transmission line that is
free of standing waves. Also see MATCHED
TRANSMISSION LINE. 2. See FLAT-RIBBON LINE.
flaw An irregularity in a substance that can result
in problems, such as mechanical failure or poor
equipment performance.
flaw detector An instrument that uses ultrasonic
waves to detect internal flaws in metal. The waves
are reflected by flaws.
F layer See F REGION.
fLb Abbreviation of FOOT-LAMBERT.
Fleming/Kennelly law Under conditions at or
near magnetic saturation in a ferromagnetic substance,
the reluctivity is directly proportional to
the intensity of the magnetic field.
Fleming’s generator rule See FLEMING’S RIGHT-
HAND RULE.
Fleming’s left-hand rule A simple way of indicating
certain relationships in the behavior of electric
generators and motors. If the thumb, index
finger, and middle finger of the left hand are positioned
so that they are at right angles to each
other, the thumb will point in the direction of
force or motion when the index finger is pointed
in the direction of flux; the middle finger points in
the direction of current flow. Compare FLEM-
ING’S RIGHT-HAND RULE.
Fleming’s motor rule See FLEMING’S LEFT-
HAND RULE.
Fleming’s right-hand rule A simple way of indicating
certain relationships in the behavior of
electric generators and motors. If the thumb, index
finger, and middle finger of the right hand are
positioned so that they are at right angles to each
other, the middle finger points in the direction of
an induced voltage, the thumb in the direction of
the motion of a conductor, and the index finger in
the direction of the magnetic field. Compare
FLEMING’S LEFT-HAND RULE.
Fletcher-Munson curves A set of curves depicting
the uneven frequency response of human hearing.
Also called AUDIBILITY CURVES.
flexible automation The ability of a robot or system
to do various different tasks. Changing from
one task to another is simply a matter of changing
software. Compare FIXED-SEQUENCE
ROBOT.
flexible collodion A viscous solution of pyroxylin
(cellulose nitrates) used sometimes as a binder
for coils.
flexible contact A contact made from flat, metal
spring stock; it is usually bent or curved. Also
called spring contact.
flexible coupling A device for joining two shafts
and conveying rotary motion from one to the
other; it is elastic, so the shafts need not be exactly
aligned with each other.
flexible flat cable See FLAT CABLE.
flexible manufacturing system A roboticized
manufacturing plant that can turn out a variety
of different products. One or more central computers
oversee the operation of the facility. Such
factories are commonly used in the production of
electronic devices (such as printed circuits, calculators,
and portable radios).
flexible resistor An insulated, wirewound resistor
that can be bent, coiled, or knotted.
flexible shaft A control shaft that can be bent
somewhat while still allowing easy adjustment.
flex life A measure of how much bending a conductor
or other flexible object can take without
breaking.
flexode A diode that is flexible in that its junction
can be changed (i.e., reversed without reversing
its leads, its resistance being variable from the
forward- to backward-resistance value).
flicker 1. A tendency for a video image to appear,
disappear, and reappear, or to increase and decrease
in intensity frequently. 2. The effect created
by such action (as in a flickering light).
flicker frequency The number of times the screen
illumination flashes on and off in the projection of
a motion picture. It is 48 per second (twice the
frame rate) in conventional movie projectors; for
each frame, the screen is blanked once when the
frame is pulled into position and once again during
projection of the frame.
flight control Electronic monitoring and control of
an aircraft in flight.
flight path The course planned for an aircraft’s
flight.
flight-path computer A computer that controls
the course of an aircraft in flight, from takeoff to
landing.
flight-path deviation The departure of an aircraft
in flight from the course in the flight plan. Also
see FLIGHT PATH.
flight-path-deviation meter An instrument that
provides a visual indication of the departure of an
aircraft in flight from the course in the flight plan.
flight telerobotic servicer A remotely controlled
robot used to maintain and repair space vehicles
and satellites. The machine can be controlled by