Wideband Digital Array Radar Technology Research

Wideband DAR is a new field of radar system, which has many advantages like the wide dynamic range, high precision, low Side-lobe, multi-object, anti-jamming, adaptive and object recognition, it's the inevitable development trend of radar and attracts more and more attentions in these years. This dissertation analyzes and studies the realization technology of wideband DAR from three aspects, the main work and creative research of this dissertation can be summarized as follows:At first, this dissertation researches transmiting technology based on Delta-Sigma. Combining the Delta-Sigma wave synthesis technology with the switching power amplifier to replace traditional DDS technology and the linear power amplifier, is the creative research of this dissertation. Contrast and analyze the scatter of signal produced by DDS and Delta-Sigma, the signal produced by Delta-Sigma have low scatter and high SNR because Delta-Sigma Modulation use the Over Sampling technology and the Noise Shaping technology. The use of switching power amplifier enable system to have high efficiency, good radiation and small volume. By establishing model and simulating, this dissertation concludes that the high speed of switching power amplifier will bring certain distortion to signal, will attenuate the frequency spectrum in signal bandwidth, the attenuation degree is inverse ratio with the over sampling rate.Secondly, this dissertation researches receiving technology based on Spectrum Intersection. This dissertation derives the receive echo detailedly and analyzes some questions in the receiving process: Researches the influence of bandpass filter on receiving performance, determins the optimum filter group frequency shift parameter, analyzes the effect of Doppler on pulse compression and wideband synthesis and testify it by performing simulation. At the same time, based on the discrete analysis method, aiming at the effect of time jitter on receiver A/D, the dissertation carries on quantificational analysis and simulation.Finally, the dissertation researches the influences of channel mismatch on system performance. The impact of amplitude and phase error in the channel on radar echo signal is analyzed by using sine ripple model and FIR stochastic model. The impacts of different channel error on digital beamforming and pulse compress are analyzed by controling model parameters. Showing that impact of mismatch on low-sidelobe beams is serious. This requires precise control of the radar receiver's frequency response across the entire signal waveform bandwidth in order to achieve low beam sidelobes and low range sidelobes.