Abstract: A high frequency amplifier comprises an amplifier stage connected in a grounded base configuration, or a plurality of such amplifier stages connected in tandem, for amplifying high frequency pulses. In order to produce high frequency pulses wherein the output power has a required pulse shape, at the emitter side of each amplifier stage a constant current source is connected which is controlled by a pulse generator which is operable to provide a current having a pulse shape which corresponds to the pulse shape which is the same as the input high frequency pulses.

Abstract: A directional coupler formed as a strip line which consists of two transmission lines coupled to each other and formed on opposite surfaces of a dielectric carrier plate with one of the lines comprising a microstrip line. A directional coupler is formed which has very high sharpness of directivity and high coupling attenuation, and great electrical strength. The second transmission line is formed as a coplanar line which includes a strip line which is mounted on the grounded side of the microstrip line in an area which is free of the grounded line surface and which extends essentially parallel and has current which is opposite to the strip line of the microstrip line. The invention is particularly adaptable for use where a directional coupler having high coupling attenuation is required, as, for example, in VSWR monitoring in secondary radar devices.

Abstract: A circuit is provided for synchronizing the oscillation U.sub.o of a pulsed oscillator with a reference oscillation U.sub.m of comparatively small amplitude. The reference oscillation is coupled into the oscillator and a phase control loop is provided in which a phase discriminator compares the phase relationship of both oscillations and provides a resulting control voltage for controlling an adjustable reactance for the frequency change of the pulsed oscillator during the leading edge of the pulse. A phase shifter, adjustable up to 180.degree., is connected between the oscillator and the phase discriminator. The output of the phase discriminator, which is highly resistive, is connected in a low-resistance manner to the adjustable reactance by way of an impedance converter, such as an emitter follower or a multi-stage wide-band amplifier.

Abstract: A circuit for synchronizing an oscillator keyed by a pulse is provided with a low amplitude reference oscillation. A phase shift regulating loop has a phase discriminator which is fed, on one hand, with a branched component of the oscillator output and, on the other hand, with the reference oscillation. The phase discriminator compares the phases of the two oscillators and emits a resultant regulating voltage an adjustable reactance for controlling the oscillator frequency during the leading edge of the keying pulse. A phase shift device, adjustable over 180.degree., is connected between the oscillator and the phase discriminator, the phase discriminator having a high-ohmic output which is connected, via an impedance converter, to the adjustable reactance.

Abstract: A pulse-modulated high-frequency transmitter is pulse keyed and has a high pulse power. A self-sustained transistor oscillator has a grounded base with a collector-emitter feedback in the form of a strip line with a length of half a wavelength and a serially-connected capacitor. A pulse modulator connected to the oscillator includes an output stage constructed as a constant current source which is keyed by a pulse generator.