AI-3
HELIX—A spirally wound transmission line used in a traveling-wave tube to delay the forward
progress of the input traveling wave.
HORIZONTAL PLANE—An imaginary plane tangent to and touching the Earth's surface as
established by a stable element, such as a gyroscope.
HORN—A funnel-shaped section of waveguide used as a termination device and as a radiating
antenna.
HOT CARRIER—A current carrier, which may be either a hole or an electron, that has
relatively high energy with respect to the current carriers normally found in majority-carrier
devices.
HOT-CARRIER DIODE—A semiconductor diode in which hot carriers are emitted from a
semiconductor layer into the metal base. Also called a hot-electron diode. An example is the
Schottky-Barrier diode.
HYBRID JUNCTION—A waveguide junction that combines two or more basic T-junctions.
HYBRID RING—A hybrid-waveguide junction that combines a series of E-type T-junctions in a
ring configuration.
IDLER FREQUENCY—In a parametric amplifier, the difference between the input signal and
the pump signal frequency. Also called the lower-sideband frequency.
INTERACTION SPACE—The region in an electron tube where the electrons interact with an
alternating electromagnetic field.
INTERELECTRODE CAPACITANCE—The capacitance between the electrodes of an
electron tube.
I2R LOSS—See Copper Loss.
IRIS—A metal plate with an opening through which electromagnetic waves may pass. Used as
an impedance matching device in waveguides.
LEAD INDUCTANCE—The inductance of the lead wires connecting the internal components
of an electron tube.
LOAD ISOLATOR—A passive attenuator in which the loss in one direction is much greater
than that in the opposite direction. An example is a ferrite isolator for waveguides that
allows energy to travel in only one direction.
LOOP—A curved conductor that connects the ends of a coaxial cable or other transmission line
and projects into a waveguide or resonant cavity for the purpose of injecting or extracting
energy.
LOOSE COUPLING—Inefficient coupling of energy from one circuit to another that is
desirable in some applications. Also called weak coupling.
MAGIC-T JUNCTION—A combination of the H-type and E-type T-junctions.
MAGNETIC FIELD—See H-field.
