Realization of a strange attractor of the Smale-Williams type in a radiotechnical delay-feedback oscillator

Based on a nonautonomous delay-feedback van der Pol oscillator, a radiotechnical circuit generating chaotic signals has been proposed and implemented, which alternatively occurs in the states of excitation and decay. This is ensured by the periodic variation of a parameter responsible for the bifurcation creating a limit cycle. The excitation of oscillations at every next activity stage is stimulated by a signal generated at the preceding stage and arriving via a delay line. Owing to a quadratic nonlinear transformation of the delayed feedback signal, the phase variable exhibits doubling at every excitation stage, which implies that the phase is subjected to circle-stretching mapping (Bernoulli mapping) with a chaotic dynamics.