Detection of Coherent Phase Modulation in Wideband Chaotic Microwave Signals

Summary form only given. It has been suggested that a new class of radars using chaotic microwave signals may have, for some applications, distinct advantages over conventional modulation schemes such as FM chirp. We will present the results of experiments on a Ku-band traveling wave tube (TWT) configured as a time-delayed feedback oscillator. A sample of the output signal was coupled back to the input of the TWT through a length of waveguide with a delay of approximately 100 nsec. The feedback gain was adjusted using a variable attenuator. Depending on the setting of the feedback level, the system generated oscillations ranging from simple periodic, through period-doubling routes to chaos, to low dimensional and finally very turbulent chaos, which had extremely wide bandwidth. The results show the degree of improvement in Doppler resolution when the bandwidth of the chaotic oscillations increases.