Usability Studies on Approximate Corrugation Models in Scattering Analysis

Abstract

Often an actual scatterer geometry is replaced with a computationally more economical model. For example, if a major part of the scatterer surface is corrugated, one solution is to analyze scattering by replacing the corrugated areas with flat impedance surfaces. But then a question arises: what is actually the error in the scattered field phase and magnitude due to this approximation? In this paper, planewave scattering from partly corrugated structures is studied. The analysis is based on integral equations (IE) and method of moments (MoM). Two-dimensional geometry and fields are assumed. TM and TE cases are analyzed separately. It is investigated how the magnitude and phase of the scattered TM and TE fields depend on the used corrugation model: exact-geometry results are compared with the approximate results in a wide frequency band. Also the phases of the TM and TE fields must be predicted correctly, if studying the polarization state of the scattered field. The paper ends with an example where a corrugated corner reflector is investigated via an exact model and via different approximate models.

Moment method analysis of plane wave scattering from planar corrugated surfaces using parallel‐plate cavity Green's functions and derivation of analytic reflection‐phase formulas for both polarizations and oblique azimuth planes

“…Before commencing the analysis, it is worth justifying its value by saying that, although Uusitupa [2006], Hanninen and Nikoskinen [2008], and Alfonso et al [2009] also dealt with plane wave scattering of corrugated surfaces using the moment method, they all suffer from shortcomings which this presently proposed approach does not. Compromise of rigor and robustness is sustained by the approach of Uusitupa [2006] which utilized restrictive slab models, whereas the method proposed in Hanninen and Nikoskinen [2008] is after all still only an approximated one due to the impedance boundary condition used. The accuracy of the treatment in Alfonso et al [2009]of finite corrugated surfaces is limited by the coarse modeling of the equivalent magnetic current over the aperture of the corrugations with sub‐domain rooftop basis functions (as opposed to entire‐domain modal ones).…”

“…In Kim et al [1999], a technique that hybridizes the method of moments with the uniform geometrical theory of diffraction (MOM/UTD) was presented for the analysis of corrugated surface‐wave antennas with an infinite ground plane and fed by a parallel‐plate waveguide. More recent works of Uusitupa [2006], Hanninen and Nikoskinen [2008], and Alfonso et al [2009] described formulations based on the method of moments to analyze the scattering of impingent plane waves from corrugated surfaces.…”

Method for measuring waveguide propagation losses by means of a Mach–Zehnder Interferometer structure

“…An analytical approach came through the so-called Asymptotic Corrugated Boundary Condition (ACBC) [131], which gives good results for a corrugation period much smaller than the wavelength [132]. Recently, a more accurate approach was proposed exploiting the Impedance Boundary Condition (IBC) associated with the corrugated surface and solving the resulting integral equation by the method of moments for 2-D structures [133] and for the 3-D ones [134].…”