Broadband Digital Array Radar Technology Research

Twenty-first Century missions present radar systems with the challenge and crisis of detecting small targets in severe clutter and against multiple sources of interference.The wideband Digital Array Radar(DAR) attracts more and more attentions from various fields of researchers and becomes hot.However,development of wideband radar systems based on the concept of DAR would face many realization obstacles. First of all,the wideband signals,especially the wide instantaneous bandwidth signals are the most difficult obstacle to DAR.This obstacle problem will be analysed and discussed and then a possible effective way to realize a wideband DAR for the usage of application will be presented.The main work and creative research of this dissertation can be summarized as follows:At first,study and analyse of the influences of wide Instantaneous bandwidth signals to the DAR.It is emphasized that the instantaneous bandwidth must be reduced because of the performance's decline of the wide instantaneous bandwidth's influences. Secondly,study and analyse of the time sequential synthetic bandwidth ways of Stepped Frequency radar and Linearly Modulated Frequency Stepped.Wideband systems can be realized and the instantaneous bandwidth problems can be reduced effectively, however,This kind of system has some problems like low data rate and serious Doppler Effect. Thirdly,present a possible effective way to realize a wideband DAR based on time simultaneous Synthetic Bandwidth and two implement architectures-one base on simple rectangle pulses and the other base on Chirp pulses. On transmit,each DAR's antenna element radiats a unique, narrow band frequency stepped waveform and a broad beam simultaneously;On receive,the signals can be combined to form narrow beams in one or more directions which will be synthesized to a wideband signal.This kind of radar has the advantages of searching and Low Probability of Intercept performances while keep the effective bandwidth as large as required.The simple rectangle pulse architecture has the restriction of pulse width because of too short too higher average transmit power while the Chirp pulses architecture can break this restriction.Finally,both the simple pulse and the Chirp pulse simultaneous synthetic way were analysed through the formulas derivation and computer simulation validation.The results show that the narrow bandwidth technology which is mature now can be used through this kind of realization way to solve the problems of wide instantaneous bandwidth's influences and low datarate and Doppler effect to radar system.