Research On Broadband Reconnaissance DBF Technology

In order to deal with greater bandwidth and more types of radar signals at the same time, radar reconnaissance receiver adopting broadband Digital Beam Forming(DBF) technology obtains good transient spatial coverage and high resolution properties through digital signal processing, beneficial to electronic reconnaissance. But the prominent problem of broadband reconnaissance DBF is: the operation bandwidth of target signal may cover several octaves, if array elements spacing(minimum spacing) is designed in accordance with the requirements of working at the highest frequency without grating lobe, design of the structure of low frequency signals is difficult and serious mutual coupling between array elements exists; And if array elements spacing(maximum spacing) in accordance with the requirements of working at the lowest frequency without mutual coupling between array elements, serious grating lobe will appear in high frequency signals.Firstly, the research background is introduced and the important significance of grating lobe suppression of wideband reconnaissance DBF is analyzed. Then the method of wideband digital beam forming and the optimal beam forming criterion are discussed. Theoretical analysis of the causes of grating lobe is presented, and the relation between array element spacing, main-lobe direction parameters and performance of grating lobe is verified by simulation. Finally, this paper focuses on the research of broadband beam grating lobe suppression technique. Against the issue of grating lobe of broadband signal beam, the technology of broadband beam-formers based on frequency weighted is studied, and its suppressing grating lobe feature is simulated and analyzed. Against the issue of grating lobe of UWB signal beam, this paper proposes a combination of local uniform array technology and grating lobe equal fluctuation array technology to suppress the grating lobe. By applying broadband beam-formers based on frequency weighted to locally uniform combined array, separate signal processing based on frequency achieves the grating lobe suppression effect. By theoretical analysis and experimental simulation of grating lobe equal fluctuation array, this paper demonstrates the suppression of UWB signal beam grating lobe effects. By comparing the two methods of local uniform array technology and grating lobe equal fluctuation array, the advantages and disadvantages of them is analyzed.