US 12,190,025 B2
Rough surface model for shooting and bouncing rays
Daniel R. Rey, Evanston, IL (US); Stefano M. Canta, Skokie, IL (US); and Robert A. Kipp, Hinsdale, IL (US)
Assigned to ANSYS, INC., Canonsburg, PA (US)
Filed by ANSYS, INC., Canonsburg, PA (US)
Filed on May 7, 2020, as Appl. No. 16/869,508.
Prior Publication US 2021/0350044 A1, Nov. 11, 2021
This patent is subject to a terminal disclaimer.
Int. Cl. G06F 30/20 (2020.01); G01S 7/40 (2006.01); G06F 17/18 (2006.01); G06F 30/15 (2020.01); G06F 30/367 (2020.01); G06F 111/08 (2020.01)
CPC G06F 30/20 (2020.01) [G06F 17/18 (2013.01); G01S 7/4052 (2013.01); G06F 30/15 (2020.01); G06F 30/367 (2020.01); G06F 2111/08 (2020.01)] 25 Claims
OG exemplary drawing
 
1. A method for computer aided electromagnetic field (EM) simulation, comprising:
simulating a projection of an EM field from a radiation source onto a surface of an object to form projected ray-tube footprints;
calculating a coherent component of a scattered field due to the EM field incident on each of the projected ray-tube footprints based on statistical characteristics of surface roughness of the surface of the object by generating a coherent scattered field based on a flat surface of the object assuming radiation from surface currents having a constant magnitude and a linear phase progression defined over a ray-tube footprint, and attenuating an amplitude of the coherent scattered field by an attenuation factor to obtain the coherent component of the scattered field, wherein the attenuation factor is a function of the statistical characteristics of the surface roughness;
calculating an incoherent component of the scattered field for each of the projected ray-tube footprints, the incoherent component being modulated by a random amplitude and a random phase based on the statistical characteristics of the surface roughness;
coherently summing the coherent component and the incoherent component for each of the projected ray-tube footprints to generate a statistically viable instance of the scattered field that includes total contributions from the coherent component and the incoherent component; and
processing the scattered field corresponding to each of the projected ray-tube footprints to represent an image of the object at an antenna based on coherently accumulating the scattered field over the projected ray-tube footprints.