Microwave Chaotic Colpitts Oscillation And Its RADAR Applications

Colpitts circuit is a well-known oscillation circuit. As the traditionalcapacitance feed-back oscillator, Colpitts circuits are extremely widely usedin signal sources from very low frequency (VLF) to millimeter wave frequenyband. In traditional applications of Colpitts circuit, what people concerned isthe harmonic resonance, and other complex non-linear effects are purposelysurpressed to obtain high quality sine wave output.In contrast, in this dissertation, what is concerned is the morecomplicated non-linear property-chaos of Colpitts circuit, especiallymicrowave chaotic Colpitts circuit, and the possibility of utilizing theultra-wide band and noise-like spectrum in constructing a new scheme chaoticRADAR system.In this dissertation, the evolution of circuit chaos from low frequency tomicrowave frequency, as well as the principle, analysis and realization ofColpitts' chaos are firstly summarized. Then, the RADAR signalcharacteristics, especially the ambiguity function of microwave Colpittssignals are analyzed, and the results turn out that such chaotic signal is with a"thumb nail" ambiguity function, implying the potential to be used as RADARsignal. At the last part of this dissertation, a system simulation to a "purechaotic" scheme RADAR, in which the wide band Colpitts chaotic signal isdirectly used as RADAR signal, and chaos synchronization is used in theRADAR signal processing, is performed. The results show that such RADARcan work in an environment of low signal-noise ratio, and has a advantage of"multi-user" property。...