18WuD2x

skin effect • slider 635
skin effect The tendency of high-frequency alternating
current to travel along the surface of a
conductor; the high-frequency reactance is lower
along the outside than at the center of a conductor.
This tends to increase the resistivity of solid
conductors at high alternating-current frequencies,
as compared with low frequencies and direct
current.
skip 1. Ionosphere-reflected radio transmissions.
2. In a computer program, an instruction whose
sole function is that of causing a jump to the next
instruction.
skip distance For a signal propagated via the ionosphere,
the distance from the transmitter to the
point at which the returned skywave strikes the
earth.
skip fading For a signal propagated via the ionosphere,
changes in signal strength caused by
fluctuations in the altitude and/or contour of the
ionized layer(s).
skip zone See ZONE OF SILENCE.
skirt selectivity 1. The bandwidth between points
of high attenuation (usually 30 dB or 60 dB) on
the selectivity curve in a communications receiver.
2. The relative steepness of the attenuation-vs.-frequency
curve in a communications
receiver.
SKM Abbreviation of sine-cosine multiplier.
skyhook 1. Colloquialism for ANTENNA. 2. A wire
antenna supported by a captive balloon or kite.
sky noise Radio noise originating in outer space.
skywave A radio wave propagated by ionospheric
reflections and/or refractions. Compare
GROUND WAVE.
Xmtr
Ionized layer
Earth
skywave
Rcvr
skywave correction A factor applied to long-range
radionavigation signals to account for the time
delay resulting from ionospheric propagation.
skywire See OUTSIDE ANTENNA.
slab 1. A relatively thick body of quartz, ceramic,
semiconductor, or dielectric. 2. See SUBSTRATE.
slap back The return of sounds by an acoustically
reflective object or surface a short distance away,
resulting in almost immediate echoes.
slashed-field-gun CRT A straight-gun television
picture tube (see STRAIGHT-GUN CRT). Because
the gap between the anodes in this tube is
slanted, the electrostatic field is diagonal, causing
the electron and ion beams to be diverted at
an angle.
slave flash A photoflash operated by the light flash
from another such unit.
slave relay A relay operated by, and whose action
follows, a MASTER RELAY.
SLC Abbreviation of STRAIGHT-LINE CAPACI-
TANCE.
sleeping sickness A gradual increase in transistor
leakage current.
sleep machine An electronic device sometimes
used as an aid for relaxation or sleeping. It consists
of a wideband audio-frequency noise generator
that produces low-level sounds similar to the
noise of waves on a beach or a light wind through
trees.
sleeve antenna A vertical antenna in which the
upper half is a quarter-wave rod connected to the
inner conductor of a coaxial feeder, and the lower
half is a quarter-wave metal sleeve connected to
the outer conductor of the feeder. Also called
COAXIAL ANTENNA.
sleeving A material in tubular form that can be
slipped over another material [e.g., insulating
sleeving for wires (spaghetti)].
slew rate In an operational amplifier, the rate at
which the output can be driven between its limits.
SLF Abbreviation of STRAIGHT-LINE FRE-
QUENCY.
slice A semiconductor wafer cut from a singlecrystal
ingot.
slicer See CLIPPER-LIMITER.
slide-back meter An electronic voltmeter in which
an unknown alternating-current signal voltage
applied to the input of an amplifier stage is
bucked by an internal, adjustable, accurately
known signal voltage. The internal voltage is adjusted
until a null occurs, indicating that its magnitude
is equal to that of the unknown voltage.
slider
First
anode
Cathode
Control grid
Strong
magnet
Weak
magnet
Ion beam
slashed-field-gun CRT
Electron
beam
A flat-spring contact that slides along the
turns of a resistance or inductance coil to vary
the coil’s resistance or inductance. Also called a
WIPER.