BOUNDARY CONDITIONSThe 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.
BEARINGAn angular measurement that indicates the direction of an object in degrees from
true north. Also called azimuth.
BUNCHER CAVITYThe input resonant cavity in a conventional klystron oscillator.
BUNCHER GRIDIn a velocity-modulated tube, the grid which concentrates the electrons in
the electron beam into bunches.
CATCHER GRIDIn 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.
CAVITY RESONATORA 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.
CHOKE JOINTA joint between two sections of waveguide that provides a good electrical
connection without power losses or reflections.
COOKIE-CUTTER TUNERMechanical magnetron tuning device that changes the frequency
by changing the capacitance of the anode cavities.
COPPER LOSSPower loss in copper conductors caused by the internal resistance of the
conductors to current flow. Also called I2R loss.
CROWN-OF-THORNS TUNERSee Sprocket Tuner.
CUTOFF FREQUENCYThe 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 waveguide.
DIELECTRIC CONSTANTThe ratio of a given dielectric to the dielectric value of a
DIELECTRIC LOSSESThe electric energy that is converted to heat in a dielectric subjected
to a varying electric field.
DIRECTIONAL COUPLERA device that samples the energy traveling in a waveguide for
use in another circuit.
DIRECTIVITYThe narrowness of the radiated beam from an antenna.