Abstract: Disclosed is a microwave load in a small-length oversized waveguide form. It comprises a body in waveguide form, made of an absorbent material with both its ends open. An oversized waveguide propagating low loss microwaves that have to be attenuated is connected to the end of the load. The cross section of the interior of the body is substantially equal to or greater than the cross section of the interior of the oversized waveguide. A mode reflecting and converting device closes the end of the load.

Abstract: The converter disclosed is interposed between a generator of electromagnetic waves and circular, output waveguide propagating the TE.sub.01 mode. It is formed by the series mounting of a rectangular waveguide, having one of its end closed and a circular waveguide propagating the TM.sub.01 mode, connected to the rectangular waveguide by a lateral opening, in such a way that the axes of the two waveguides are perpendiuclar, also included in the series mounting is a group of intermediate waveguides placed after the circular waveguide, distributed in a ring before its free end. Each intermediate waveguide is formed by a sequence of waveguide pieces working in the rectangular TE.sub.10 mode and gradually offset in rotation with respect to one another, in the same direction. The overall offset among the pieces of one and the same intermediate guide will be 90.degree.. The converter can be applied to the conversion of modes in high power microwave transmission circuits.

Abstract: Disclosed is a power divider in waveguide form, for a microwave power transmission circuit, working at high power in the rectangular TE.sub.10 mode. This power divider is formed by the juxtaposition of:a rectangular, input waveguide working in its fundamental mode, receiving the power to be divided through one of its ends, and having another closed end;a circular waveguide propagating the TM.sub.01 mode connected to the rectangular, input waveguide by a lateral opening in such a way that the axes of the two guides are perpendicular;a group of n output waveguides, placed at the output of the circular waveguide and distributed in a ring before its free end, working in the TE.sub.10 mode, each transmitting a fraction of the power introduced into the input. The device can be applied to microwave power transmission circuits.

Abstract: The microwave oscillator is formed by a free oscillator 1 coupled with two surface or volume acoustic wave delay lines 9 and 10 connected in series or in parallel and operating by reflection. The first line imposes a delay 2.tau..sub.1, corresponding to one reciprocation, which is a multiple of the delay 2.tau..sub.2 imposed by the second line, and a=.tau.1/.tau.2 is preferably equal to 2 or 3. Application to oscillators operating at ultra-high frequencies, particularly in the L-band.

Abstract: A distortion-corrector which comprises a filter of the low-pass type, of the .pi. or T configuration, and two diodes, in parallel opposition, disposed between the input and output of the filter. This corrector compensates amplitude-and-phase- distortions of the tube associated with the corrector, over a given operational frequency-band of the tube which is below the cut-off frequency of the filter, by compressing weak signals, for which no diode conducts, with respect to strong signals, for which there is at least a start of conduction of one of the diodes and by producing a phase-lead which increases with the input power of the tube.