Chaff jamming is one of the most commonly used passive jamming methods,and mainly depends on its electromagnetic scattering characteristics to jam radar receivers.In this paper,the radar cross section(RCS)of chaff scattering is studied,and the average RCS of a single chaff under different incident polarization conditions is derived by using incoherent model.The scattering ma-trix of chaff polarization is obtained,and the polarization scattering characteristics of single chaff are analyzed.An ideal placement model under coherent conditions is proposed,and the average RCS value of a single chaff is obtained,which is more close to the actual use,and lays a foundation for giving full play to the passive jamming efficiency of chaff.
Aiming at the requirement of accurate reconnaissance to dense targets,a sorting correla-tion method based on multi-dimensional feature fuzzy weighting is proposed.Firstly,the member-ship degree of each dimension parameter is measured by nonlinear Euclidean distance,then the membership degree of different parameter dimensions is fuzzily weighted by weight,and finally the sorting correlation is carried out according to the final weighted membership degree.The simula-tions of different scenes with medium and high repetition frequency show that the proposed method can carry out correct sorting correlation for dense targets with overlapping electromagnetic param-eters,also the algorithm is not sensitive to parameter setting and has good robustness.
In order to accurately estimate the influence of troposphere atmospheric environment on the absorption and attenuation of electromagnetic wave energy,and provide theoretical basis for the measurement equipment of electromagnetic wave emission to estimate the operating distance,measurement and control arrangement and radiation safety zone setting,the attenuation effect of troposphere atmospheric absorpting gas on electromagnetic wave energy propagation is studied.According to the suggestions of Rec.ITU-R P.676-9 of the International Telecommunication U-nion and the approximate estimation model of atmospheric attenuation rate,the equivalent altitude calculation model and the equivalent path refraction model for 1～54 GHz electromagnetic wave given by GJB/Z 87-97"Radar Wave Refraction and Attenuation Manual",the calculation model of electromagnetic wave inclined path attenuation across the equivalent height in the troposphere is revised and improved.The influence of different atmospheric pressure,temperature and water va-por density on the attenuation rate,and the influence of different propagation elevation,tempera-ture and relative humidity on the energy attenuation of electromagnetic wave at the same propaga-tion distance are studied by simulation.
This paper analyzes the strength,stiffness and vibration mode of busbar structure for high voltage electric slip ring for the single point mooring system.The simulation results show that the structure satisfies the usage conditions of strength and stiffness,but has a less first-order natu-ral frequency,which may result in structural resonances in transportation or engineering applica-tions,thereby there are certain security risks.Under the premise of ensuring the high voltage cur-rent-carrying performance of the bus structure,by increasing the structural size of the high-pres-sure casing,and adding a stainless steel sheet structure with a boss on the busbar,the structural stiffness is enhanced,vibration mode feature is changed,feature frequency intervals emerged possi-bly are avoided,which effectively improves the operational safety of the electric slip ring in vibra-tion environment.
According to the requirements of high flexibility of low side lobes for planar phased ar-ray,this paper proposes a weighting method for planar array based on asymmetric Taylor synthe-sis.Compared with the existing mainstream methods,this method can apply to planar arrays with random array arrangement,can perform asymmetric side-lobe control to the radiation pattern,and has the advantages of small antenna gain loss,simultaneous weighting of amplitude & phase and algorithm being non-iterative.This paper provides both symmetric and asymmetric Taylor weigh-ting formulas,as well as the side-lobe descending effect under different fronts arrangement.The simulation results show that the proposed method has fast speed,high flexibility and stable per-formance.
