A recent e-mail from a long-time reader conjured up memories of the early days of computers, back when data was stored on floppy disks. In those days, many engineers (this writer included) were in search of whatever design "freeware" they could find, whether it was for creating simple bandpass filters or synthesizing matching circuits for amplifiers. Software was available back then, free or low in cost, and these programs often served as excellent starting points for a design. But they were far from accurate andas anyone who remembers the rudimentary design programs of those days can attesthad little or nothing in terms of a user interface. Using some of these tools typically involved writing lines of code as inputs.
Most design programs worth their salt lean on James Clerk Maxwell in some way, using his electromagnetic (EM) field equations or Poisson's derivatives to solve for fields around a conductor. EM simulators were nonexistent in the early days of computers. For one thing, the computing power needed to solve these equations just wasn't there. Even now, calculations by EM simulators to find S-parameters for complex circuits can take a while. Generally speaking, however, EM simulators have come a long way. Accurate and essential, they are no longer a "luxury" in a designer's software toolkit. And when compared to the time spent building and testing a prototype circuit (then repeating the process in an attempt to optimize it), the processing time of an EM simulator doesn't look so badespecially when it can save at least one prototype iteration.