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Technical
Glossary - L
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| D | E
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| R | S
| T | U,V
| W,X,Y,Z | Spec.
Char., Number |
Lambda
(See "wavelength")
LAN
Local area network. A data communication network
operating within a building or small group of
buildings.
Laser
Light amplification by stimulated emission and
radiation. A device that generates or amplifies
light by means of a medium that provides optical
gain. Common types of lasers include solid state
(glass or cystalline bulk material), semiconductor
(based on p-n junctions), and gas lasers. Fiber
lasers are doped glass lasers designed to amplify
the light in optical fibers.
L-Band
The frequency interval from 1 to 2 GHz.
Limiter
A receiver protector that allows low power signals
to propagate from the antenna of a receiver to
the next sensitive stage, such as a mixer or LNA,
but rejects high power signals that may be incident
on the antenna. Limiters are typically self-actuating
but may also be controlled by an external bias
signal.
Linear
A circuit or component whose transfer function
can be accurately described by a first order equation
(a straight line, hence the term linear).
Linearity
For an attenuator, the variation from the best
straight line of the attenuation versus control
signal transfer function at center frequency,
measured in dB or percentage of attenuation. For
a VCO, the variation best straight line of the
output frequency versus control signal transfer
function, measured in per cent. For a system or
component: the extent to which the output spectrum
is identical to the input spectrum. A system that
generates spurious signal is considered to be
nonlinear.
LMDS
Local multipoint distribution service. Any service
providing high-speed transmission of voice and
data from single distribution points to multiple
users. Generally, LMDS provides wireless broadband
communications to small and medium-sized companies
or to apartment buildings.
LNA
(See "Low Noise Amplifier")
LO
(See "Local Oscillator")
Load
A device or impedance that terminates the output
of a device or transmission line. A load is typically
a resistance, the magnitude of which is equal
to the characteristic impedance of the transmission
line.
Local
Oscillator
A reference signal generating circuit that is
contained within a receiver or transmitter. The
LO signal provides the high frequency bias to
a mixer. The local oscillator signal is typically
at a higher power than the signal power. An optimum
local oscillator power is required to obtain low
conversion loss and good RF match to the mixer
non-linear impedance component. Normally optimum
local oscillator powers are in the range of -3
to +13 dBm for most common diodes or FET's.
Loss
Reduction in signal power.
Low
Noise Amplifier
An amplifier with low noise figure that is typically
used at the front end of a radio receiver.
Low
Pass Filter
A reactive circuit that rejects signals whose
frequencies are above the 3 dB point frequency
and propagates signals whose frequencies are below
the 3 dB point frequency.
LPF
(See "low pass filter")
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