Abstract: An element with periodic structure for guiding electromagnetic waves propagating along a longitudinal axis of the structure at a speed below the velocity of light is disclosed. The structure includes a series of metal polar expansions aligned with the mentioned axis and forming a plurality of resonant metal cavities. The polar expansions have respective apertures aligned with each other so as to form a freeway for electron flow. First and second conductors are provided for cooperating with the polar expansions. The polar expansions each further respectively have first and second apertures for receiving first and second conductors that are preferably positioned diametrically opposed to each other with respect to the mentioned longitudinal axis.

Abstract: A traveling-wave tube has coupled cells in a periodic arrangement defined between apertured irises separated by respective spacers. The spacers have dielectric waveguides terminating in lossly loads to attenuate RF frequencies above the upper limit of the frequency to be amplified by the tube.

Abstract: Two variable-frequency microwave generators, i.e. a coaxial magnetron producing outgoing waves and a voltage-controlled oscillator emitting a heterodyning signal for incoming waves of a radar transceiver, are continuously tuned by a pilot signal modifying their operating frequencies with a predetermined constant separation. To maintain this correlation, the tuning circuit of at least one microwave generator responds to the pilot signal through the intermediary of a read-only memory which, on being directly or indirectly addressed by that signal, emits stored setting instructions for the respective generator.

Abstract: A resonant cavity of a microwave generator, such as a magnetron oscillator, is provided with a tuning piston which is rectilinearly displaceable between two terminal positions, corresponding to respective limiting frequencies, by means of a rotating crankshaft whose eccentric portion constitutes the inner race of a ball or roller bearing. The outer race of that bearing rolls, directly or through the intermediary of a captive spherical or cylindrical coupling member, on a transverse face of the tuning piston held in contact therewith by spring pressure.

Abstract: A klystron oscillator has an input cavity resonant in a TM.sub.010 mode and a larger output cavity resonant in a TM.sub.OnO mode where n is an integer greater than 1, preferably equal to 2. The input cavity, with re-entrant bosses defining a buncher gap, projects into the output cavity to form one of two re-entrant bosses thereof defining a catcher gap.

Abstract: A magnetron with a central cathode coaxially surrounded by an annular anode forming an array of cylindrical resonant cavities is tunable by an axially movable disk carrying hollow plungers which project into these cylinders, the disk being spacedly overlain by a lid or wall member defining therewith a shallow chamber for the circulation of a cooling fluid. The fluid enters and leaves via expandable inlet and outlet channels to traverse not only the chamber but also the interior of the several plungers. The axial adjustment of the disk is brought about by rotation of a ring with an internally threaded hub engaging a complementarily threaded hollow boss rigid with the disk, the chamber communicating with the interior of the boss through peripheral apertures of the latter. The fluid is branched off a hydraulic circuit for the cooling of the stationary electrode structure formed by the anode and the cathode.

Abstract: A resonant cavity of a microwave generator, such as a magnetron oscillator, is provided with a tuning piston which is displaceable between two terminal positions, corresponding to respective limiting frequencies, by means of a rotating crank-shaft whose eccentric portion is hugged by a nonrotatable follower ring suspended between two flexible wires or blades extending generally radially outward from diametrically opposite points of the ring. A yoke spacedly surrounding the ring is provided with two oppositely extending tubular arms in which the wires or blades are received with clearance while being fastened to the ends of these arms remote from the yoke; the tuning piston is rigidly connected with one of the two arms.

Abstract: A resonant cavity of a microwave generator, such as a magnetron oscillator, is provided with a tuning piston which is displaceable between two terminal positions, corresponding to respective limiting frequencies f.sub.1 and f.sub.2, by means of a rotating crankshaft to which the piston is coupled by a linkage including a pitman with a substantially linearly guided extremity remote from the crankshaft axis. The length p of the pitman, measured between the pivotal axes of its extremities, is related to the eccentricity e of the crankshaft by the expression ##EQU1## where q is the length of the stroke of the linearly guided extremity between its extended dead-center position and an intermediate position in which the operating frequency of the generator has its mean value (f.sub.1 +f.sub.2)/2. With this dimensioning, the frequency varies as a sinusoidal function of the crankshaft angle and is therefore proportional to the output voltage of an angle sensor coupled with the crankshaft.

Abstract: A self-exciting oscillator comprises a klystron with an input cavity and an output cavity, interconnected by a feedback port, which resonate at fractionally different frequencies in the microwave range. The output cavity, alone, is tunable to vary the operating frequency within a range of about .+-.2%.