Theoretical and Experimental Investigation of an L-band Chaotic Oscillator #

Abstract

An L-band microwave buffered chaotic oscillator is designed and realized on a glass teflon hybrid technology. The buffers are optimized in order to match the microwave 50 Ω − 12 GHz oscilloscope without changing significantly the chaotic output characteristic. Dynamical behaviours of the oscillator are theoretically investigated using both numerical studies based on mathematical model and ADS software simulation. First of all, the theoretical study is based on the Matlab simulation, where transistors are modeled by simple mathematical description which is limited only for low frequencies. Nevertheless, it provides a valid approximation to broach a preliminary theoretical investigation. Here, times series, phase portraits, Lyapunov exponents and bifurcation diagrams of the chaotic system are performed. Secondly, in order to account for the increasing frequency, we use the ADS software simulation in which the transistor is described by a high frequency model. Indeed, the impact of microstrip critical lines interconnections and active probes are taken into account in ADS simulations. Spectral and time-domain measurements on the 3.6 GHz spectrum analyzer and 12 GHz oscilloscope are achieved. Experimental characterization gives a fundamental frequency of 2.14 GHz. This microwave chaotic oscillator exhibits attractive spectral characteristics. A good agreement between theoretical and experimental results is obtained.