Research On Efficient Algorithm For Electromagnetic Scattering From Cavities With Partial Modification

With the development of modern detection technology,higher requirements have been placed on the electromagnetic stealth performance of aircraft.When assessing the electromagnetic stealth performance of an aircraft,it is both important and difficult to design a stealth design for a strong scattering cavity such as an air intake duct and a tail nozzle on the aircraft.When we do the simulation analysis and design,the cavity shape and the coating of the absorbing material need to be modified several times.Each time the traditional simulation method is used,it needs to be recalculated.The simulation process is bound to consume a lot of time.Therefore,it is of great theoretical significance and engineering application value to develop a fast algorithm for the electromagnetic scattering characteristics of local changes in the cavity.The main research work of this paper is as follows:1.The Kirchhoff approximation formula is introduced into the magnetic field integral equation satisfied on the inner surface of the cavity,and the mathematical model of the cavity moment method is established.Numerical examples verify the correctness of the method.This method can effectively eliminate the influence of electromagnetic scattering contribution from the outer wall of the cavity when calculating the radar scattering cross section of the cavity scattering.2.The cavity method of moments is combined with the part modification algorithm,and a part modification algorithm for an ideal conductor cavity is proposed.The voltage matrix and RCS calculations are accelerated.Numerical simulations were performed for the case where the cavity terminal and cavity mouth shape were modified multiple times.The results show that the method has high computational efficiency.3.Calculating the case where the absorbing medium layer is coated on the surface of the cavity,the part modification algorithm of the ideal conductor cavity is extended to the part modification algorithm of coating the absorbing dielectric layer cavity through the impedance boundary condition.Numerical calculation of the effect of local changes in cavity coating on RCS.