AI-2
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 repeller voltage.
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.
ELECTRON SPIN—The 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 propagation.
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.
GRID-GAP 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.
