Research On Fast PO Algorithm Using Fresnel Zone

Nowadays for various electromagnetic engineering applications, analysis of the scattering characteristics of electrically large objects is an important issue. There is an urgent need for its development. While traditional low-frequency methods and traditional high frequency methods can not meet the need for the computation of complex system. Though Physical Optics(PO) method is an efficient high frequency method, for very large surfaces, the computational cost is still very expensive.Based on this background, this paper comes up with a method to solve electrically large size objects’ scattering problem which have smooth surfaces. Due to the locality of the scattered fields, only parts of the PO currents contribute significantly to the scattered field. So we can only compute on these areas to reduce the unknowns on the platform. So is the electrically large size object. This paper proposes a geometry approximation method to decide the Fresnel zones for a given scatterer and observation point over a large smooth PEC planar surface to avoid bringing in computation complexity. The method uses Generalized Transition Matrix(GTM) to solve complex system or a complex scatterer because it is defined uniquely to describe the relationship between the out-going fields and the incident fields on a specified reference surface. So we can choose a simple reference surface and use GTM to calculate the fields to get a good computational efficiency.