| The Ultra-wideband(UWB)technology is a new type of wireless communication technology developed rapidly in recent years,it uses very narrow pulse as transmission carriers,so the UWB has the advantages of high transmission rate,big bandwidth,low spectral density,and strong anti-interference ability and so on,it is widely used in military communication,Wireless Local Area Network(WLAN),Radar positioning and other fields.The sub-cycle microwave pulse is an important transmission carrier in UWB technology,the bandwidth of the pulse is in GHz.It will help to make the pulse play a better application in UWB technology field through studying the characteristics of thesub-cycle microwave pulse.In this thesis,the main work and research content include:First,this thesis plays a circuit scheme of the sub-cycle pulse generation,and uses the function of the Symbolically defined devices(SDD)in the software of Advanced Design System(ADS)to modeling the Step-Recovery Diode(SRD),then places the model in the entire circuit for simulation to get the optimal circuit parameters.After,we actually make a circuit base on the theoretical design.Experimental results show that the circuit is able to produce sub-cycle microwave pulse of 150ps(FWHM),with 3.7V pulse amplitude and 3.2GHz bandwidth(-10dB).Second,because of the sub-cycle microwave pulse is unipolar,it can't spread in the free space,therefore,this thesis designs a simple and practical dipole antenna to receive and transmit the sub-cycle pulse signal though the simulation software of HFSS.The dipole antenna can help us to get the time domain waveform of the sub-cycle pulse in the free space.Finally,this thesis uses the time-frequency analysis method of Wigner-ville(W-V)to analyse the time domain pulse signal in the free space,the analysis results show the existence of the intrinsic chirp in the time domain pulse signal,it means the instantaneous frequency of the time domain signal pulse changes over time. |
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