Comparison of Electromagnetic Scattering Solutions Using the Disk as a Target

摘要

Results are compared for scattering from a perfectly conducting circular disk using three solutions: A closed form physical optics (PO) solution, a Physical Theory of Diffraction (PTD) solution, and a computer implementation of an exact eigenfunction solution. The far field patterns are compared for various ka values as well and incidence angles for both vertically and horizontally polarized electric fields. For normal incidence, the solutions agree very well. For small ka the agreement is remarkable. As ka increases, the agreement is still good as long as the observation angle, theta, does not exceed 45 degrees. The applicability of using the disk as a target to calibrate an RCS measurement range is discussed. The disk calibration curve is a plot of the specular return as a function of bistatic angle. This curve is computed for both horizontal and vertical polarizations and various ka values using the PO and eigenfunction solutions. The specular bistatic RCS (calibration curve) is relatively invariant; hence, the disk is an ideal candidate as a calibration standard for bistatic RCS measurements. Agreement between the PO and eigenfunction solutions for large ka means there is an easy method of generating the applicable calibration curve for a particular disk as long as one remains within the valid angular region for a proper size disk.