Integral equation techniques: From microwaves, over mm waves, to IR and optical frequencies

Computational electromagnetics has become a real cornerstone in the design of microwave and millimeter wave components and systems. One of the major computational techniques used in these designs is to solve integral equations with the Method of Moments (MoM). Traditionally, MoM has been used extensively for antennas, transmission lines, filters, couplers, etc., mainly in the MHz and GHz range. However, MoM can also be applied at much higher frequencies. It will be shown that at these frequencies, this computational technique is just emerging. One of the reasons is that there are serious differences with the classical implementations, which prohibits the direct use of the well-known commercially available MoM solvers. For example, one of the differences is the fact that the concept of a surface current, confined to a very thin layer at the surface of a conductor, is not valid any more. In this presentation, the different computational techniques will be reviewed and compared, not only in the traditional microwave and millimeter wave range, but especially at THz, IR, and optical frequencies. In concreto, the MAGMAS MoM solver will be compared to a numerical FDTD solver well-known in the plasmonics research community: Lumerical. It will be shown that also at these very high frequencies, MoM has its proper place in the pallet of computational algorithms.