A microwave generator (11) has a parallel connection of series connections of uncontrolled discharge spark gaps (13) and charge storage means (12) which are charged up by way of charging resistors (17) and an inductor (19) common to all parallel connections, from a high voltage generator (26), until the respective spark gaps (13) short-circuit by way of arcs and the storage means (12) are discharged again by way of the inductor (19). The oscillating short-circuit currents which thus occur in stochastic steep-edged manner and which are superimposed on each other in the inductor (19) are emitted by way of an antenna (21) connected in single-pole manner thereto in the form of a high-energy microwave spectrum which is wide-band in accordance with the arc switching speed, with a spectral key point which is determined by the inductor (19). Such an operative system which can be used as a non-lethal interference or jamming device in relation to communication connections and in relation to the function of electronic circuits can be embodied in the size of a manually portable case or also in the form of a payload for a submunition projectile, a rocket or a drone and can thus be used over a wide operative range.