[[EM.Picasso]] (<b><iti>P</iti></b>rinted Circuit and Antenna System Simulator and Optimizer) is a simulation software tool for analysis and design of planar microwave circuits and antennas. It features a computationally efficient simulation engine that is based on the 2.5D Method of Moments (MoM). The method of moments is a full-wave integral-equation-based numerical technique for solving Maxwellâs equations. Rather than discretizing the entire computational domain, MoM takes advantage of the analytical solutions that might be available for the background structure to reduce the mesh size significantly. This is embodied in the form of dyadic Greenâs functions, which are indeed the solutions to the background boundary value problem with elementary sources. MoMâs highly reduced mesh size can lead to faster computation times and lesser memory requirements. This is particularly important for antennas and other open-boundary structures. In such cases, the appropriate Greenâs functions take care of the unbounded background medium of the problem, which inherently has infinite extents.
Unlike FDTD, which has a very general nature, the applicability of the mehtod of moments depends on the availability of the Greenâs functions for a given problem. For many planar microwave circuits and antennas, the background structure is a layered planar substrate. This consists of a vertically stacked configuration of one or more dielectric layers of infinite lateral extents. From the top and bottom, the stack-up may end in either the free space, or an unbounded dielectric half-space, or perfect electic conductor (PEC) ground or a perfect magnetic conductor (PMC) ground. There are Greenâs function solutions for such multilayer planar structures, albeit not in closed form and involving recrusive algorithms. [[EM.Picasso]] carries out all these mathematically complex computations behind the scenes during a MoM simulation.