Abstract: A power amplifier for microwave signals, the amplifier comprising a plurality of identical transistors, wherein: the grid buses of two adjacent transistors are interconnected by a grid matching circuit; the drain arrays of two adjacent transistors are interconnected by a drain matching circuit; the grid matching circuits are selected in such a manner as to ensure input levels to each transistor that are identical in amplitude and in phase; and the drain matching circuits are selected in such a manner as to present each transistor with optimum power impedance. The amplifier input is on the grid bus of a transistor at one end of the series connection of transistors and the amplifier output is on the drain array of a transistor at the other end of the series connection of transistors. It is thus possible to assemble an arbitrary number of transistors in a power amplifier, while providing an amplifier that occupies a smaller area.

Abstract: To implement a high-gain amplifier in a microwave frequency band, it is proposed to interconnect amplification circuits and to cover the housing that contains them with a lid. In the space between the lid and the amplification circuits, inside the housing, waveguides are provided whose cutoff frequency is such that it allows none of the modes that can be present at the frequencies of the working band to propagate. It is shown that, by forming such waveguides in said space, instead of filling it with absorbents, much better radio isolation is obtained between the output and the input to avoid interfering reinjections. As a result, in the same housing, it is possible to achieve amplification of up to 90 dB, whereas, hitherto, the limit of 45 dB per housing could not be exceeded.