Module 11—Microwave Principles
Pages i - ix
1-1 to 1-10
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1-21 to 1-30
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, 1-51 to 1-60
1-61 to 1-68
, 2-1 to 2-10
2-11 to 2-20
,2-21 to 2-30
2-31 to 2-40
, 2-41 to 2-50
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3-1 to 3-10
, 3-11 to 3-20
AI-1 to AI-6
, Index-1 to Index-2
Assignment 1 - 1-8
Assignment 2 - 9-16
BOUNDARY CONDITIONS—The two conditions that
the E-field and H-field within a waveguide must meet before energy will travel down the waveguide. The E-field
must be perpendicular to the walls and the H-field must be in closed loops, parallel to the walls, and
perpendicular to the E-field.
BEARING—An angular measurement that indicates the direction of an object in
degrees from true north. Also called azimuth.
BUNCHER CAVITY—The input resonant cavity in a conventional
BUNCHER GRID—In a velocity-modulated tube, the grid which concentrates the electrons
in the electron beam into bunches.
CATCHER GRID—In a velocity-modulated tube, a grid on which the spaced
electron groups induce a signal. The output of the tube is taken from the catcher grid.
space totally enclosed by a metallic conductor and supplied with energy in such a way that it becomes a source of
electromagnetic oscillations. The size and shape of the enclosure determine the resonant frequency.
JOINT—A joint between two sections of waveguide that provides a good electrical connection without power losses or
COOKIE-CUTTER TUNER—Mechanical magnetron tuning device that changes the frequency by changing
the capacitance of the anode cavities.
COPPER LOSS—Power loss in copper conductors caused by the internal resistance of the conductors to current
flow. Also called I2R loss.
CROWN-OF-THORNS TUNER—See Sprocket Tuner.
frequency at which the attenuation of a waveguide increases sharply and below which a traveling wave in a given
mode cannot be maintained. A frequency with a half wavelength that is greater than the wide dimension of a
DIELECTRIC CONSTANT—The ratio of a given dielectric to the dielectric value of a vacuum.
LOSSES—The electric energy that is converted to heat in a dielectric subjected to a varying electric field.
DIRECTIONAL COUPLER—A device that samples the energy traveling in a waveguide for use in another circuit.
DIRECTIVITY—The narrowness of the radiated beam from an antenna.
DOMINANT MODE—The easiest mode to produce in a waveguide, and also, the most efficient mode in terms
of energy transfer.
DRIFT SPACE—In an electron tube, a region free of external fields in which relative
electron position depends on velocity.
DUMMY LOAD—A device used at the end of a transmission line or
waveguide to convert transmitted energy into heat so no energy is radiated outward or reflected back.
E-FIELD—Electric field that exists when a difference in electrical potential causes a stress in the dielectric
between two points.
E-TYPE T-JUNCTION—A waveguide junction in which the junction arm extends from the main
waveguide in the same direction as the E-field in the waveguide.
ELECTRIC FIELD—See E-field.
ELECTRONIC TUNING—In a reflex klystron, changing the frequency and output power of the tube by altering the
ELECTROLYSIS—Chemical changes produced by passing an electrical current from one
substance (electrode) to another (electrolyte).
ELECTRON ORBITAL MOVEMENT—The movement of an electron around the nucleus of an atom.
movement of an electron around its axis.
ELEVATION ANGLE—The angle between the line of sight to an object
and the horizontal plane.
FARADAY ROTATION—The rotation of the plane of polarization of electromagnetic
energy when it passes through a substance influenced by a magnetic field that has a component in the direction of
FERRITE—A powdered and compressed ferric oxide material that has both magnetic properties and resistance
to current flow.
FERRITE SWITCH—A ferrite device that blocks the flow of energy through a waveguide by
rotating the electric field 90 degrees. The rotated energy is then reflected or absorbed.
TUNING—A method of changing the center frequency of a resonant cavity by physically changing the distance between
the cavity grids.
GROUP VELOCITY—The forward progress velocity of a wave front in a waveguide.
H-FIELD—Any space or
region in which a magnetic force is exerted. The magnetic field may be produced by a current-carrying coil or
conductor, by a permanent magnet, or by the earth itself.
H-TYPE T-JUNCTION—A waveguide junction in which
the junction arm is parallel to the magnetic lines of force in the main waveguide.
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.
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
INTERELECTRODE CAPACITANCE—The capacitance between the electrodes of an electron tube.
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
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.
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.
METALLIC INSULATOR—A shorted quarter-wave section of transmission line.
portion of the electromagnetic spectrum from 1,000 megahertz to 100,000 megahertz.
MODULATOR—A device that
produces modulation; i.e., varies the amplitude, frequency, or phase of an ac signal.
ELEMENT—A component having an operating region in which an increase in the applied voltage increases the
resistance and produces a proportional decrease in current. Examples include tunnel diodes and silicon unijunction
NONDEGENERATIVE-PARAMETRIC AMPLIFIER—A parametric amplifier that uses a pump signal frequency
that is higher than twice the frequency of the input signal.
PHASE SHIFTER—A device used to change the
phase relationship between two ac signals.
POWER GAIN—The ratio of the radiated power of an antenna compared to the output power of a standard antenna. A
measure of antenna efficiency usually expressed in decibels. Also referred to as POWER RATIO.
RATIO—See Power Gain.
PROBE—A metal rod that projects into, but is insulated from, a waveguide or resonant
cavity and used to inject or extract energy.
PUMP—Electrical source of the energy required to vary the
capacitance of a parametric amplifier.
RANGE—Distance, as measured from a point of reference, such as a
radar, to a target or other object.
REACTANCE AMPLIFIER—A low-noise amplifier that uses a nonlinear
variable reactance as the active element instead of a variable resistance. Also called a parametric amplifier.
RECIPROCITY—The ability of an antenna to both transmit and receive electromagnetic energy.
KLYSTRON—A klystron with a reflector (repeller) electrode in place of a second resonant cavity to redirect the
velocity-modulated electrons back through the cavity which produced the modulation.
ratio of the phase velocity of a wave in free space to the phase velocity of the wave in a given substance
REPELLER—Sometimes called a reflector. An electrode in a reflex klystron with the primary
purpose of reversing the direction of the electron beam.
ROTATING JOINT—A joint that permits one section of a transmission line or waveguide to rotate continuously
with respect to another while passing energy through the joint. Also called a rotary coupler.
SKIN EFFECT—The tendency for alternating current to concentrate in the surface layer of a conductor.
The effect increases with frequency and serves to increase the effective resistance of the conductor.
SLOT—Narrow opening in a waveguide wall used to couple energy in or out of the waveguide.
Also called an
aperture or a window.
SPROCKET TUNER—Mechanical tuning device for magnetron tubes that changes the
frequency of the cavities by changing the inductance. Also called a crown-of-thorns tuner.
TUNING—A method of klystron tuning in which the resonant cavities are tuned to slightly different frequencies to
increase the bandwidth of the amplifier.
STANDING WAVE RATIO—The ratio of the maximum to the minimum amplitudes of corresponding components of a
field, voltage, or current along a transmission line or waveguide in the direction of propagation measured at a
SYNCHRONOUS TUNING—In a klystron amplifier, a method of tuning which tunes all the resonant cavities to
the same frequency. High gain is achieved, but the bandwidth is narrow.
TRANSIT TIME—The time an electron
takes to cross the distance between the cathode and anode.
TRANSVERSE ELECTRIC MODE—The entire electric
field in a waveguide is perpendicular to the wide dimension and the magnetic field is parallel to the length. Also
called the TE mode.
TRANSVERSE MAGNETIC MODE—The entire magnetic field in a waveguide is perpendicular to
the wide dimension ("a" wall) and some portion of the electric field is parallel to the length. Also called the TM
TUNNELING—The piercing of a potential barrier in a semiconductor by a particle (current carrier) that does
not have sufficient energy to go over the barrier.
TUNNEL DIODE—A heavily doped junction diode that has
negative resistance in the forward direction over a portion of its operating range. See NEGATIVE-RESISTANCE
VARACTOR—A PN-junction semiconductor designed for microwave frequencies in which the capacitance varies with
the applied bias voltage.
VARIABLE ATTENUATOR—An attenuator for reducing the strength of an ac signal
either continuously or in steps, without causing signal distortion.
VELOCITY MODULATION—Modification of
the velocity of an electron beam by the alternate acceleration and deceleration of electrons.
PLANE—An imaginary plane that is perpendicular to the horizontal plane.
WAVEGUIDE—A rectangular, circular,
or elliptical metal pipe designed to transport electromagnetic waves through its interior.
OF OPERATION—Particular field configuration in a waveguide that satisfies the boundary conditions. Usually divided
into two broad types: the transverse electric (TE) and the transverse magnetic (TM).
WAVEGUIDE POSTS—A rod of conductive material used as impedance-changing devices in waveguides.
WAVEGUIDE SCREW—A screw that projects into a waveguide for the purpose of changing the impedance.
WOBBLE FREQUENCY—The frequency at which an electron wobbles on its axis under the
influence of an external magnetic field of a given strength.
Introduction to Matter, Energy, and Direct Current,
to Alternating Current and Transformers, Introduction to Circuit Protection,
Control, and Measurement
, Introduction to Electrical Conductors, Wiring Techniques,
and Schematic Reading
, Introduction to Generators and Motors
Introduction to Electronic Emission, Tubes, and Power Supplies,
Introduction to Solid-State Devices and Power Supplies
Introduction to Amplifiers, Introduction to
Wave-Generation and Wave-Shaping Circuits
, Introduction to Wave Propagation, Transmission
Lines, and Antennas
, Microwave Principles,
, Introduction to Number Systems and Logic Circuits, Introduction
to Microelectronics, Principles of Synchros, Servos, and Gyros
Introduction to Test Equipment
, Radar Principles,
The Technician's Handbook,
Master Glossary, Test Methods and Practices,
Introduction to Digital Computers,
Magnetic Recording, Introduction to Fiber Optics