Chaos in microwave oscillators

Chaos is one of the more interesting recent developments in the area of nonlinear dynamics. It is found that microwave oscillators, being highly nonlinear and rather complex, are prone to chaos. In general chaotic behaviour of a dynamical system is characterised by: 1) extreme sensitivity to initial boundary conditions; 2) apparent internal randomness, viz. a messy and continuous frequency spectrum; 3) fractal dimension of its attractor; and 4) positive sign Lyapunov exponents. Having investigated, as an example, two microwave oscillators, we have found that they have in common a physical mechanism, which is responsible for their nonlinear dynamical behaviours and chaos.