Computer-aided engineering (CAE) has been a part of this industry in some shape or form since the 1960s, growing from a curiosity into a crutch. Naturally, as computers have gotten better, the software that goes with them has also improved, and many RF/microwave-related CAE software tools represent the cumulative knowledge of many years of design experience from some of the top minds in this industry. There is an easy tendency to load the software and let it do all the design work, trusting completely in the results.
More often than not, this can save a great deal of trial-and-error effort as part of the design procedure, and yield typically excellent results. But it may not bring about that moment of insight or inspiration that many engineers have experienced as part of their on-the-job learning process—that moment when everything looked so clear that even a child could do it. Sometimes, attaining that special moment is worth suffering through the trials and tribulations of designing, prototyping, and testing. It is a feeling of accomplishment that is difficult to capture in any CAE program.
Of course, in an issue devoted to design and simulation software, it may seem odd to criticize such software here, and that is not the intention. The strides that computers and engineering software programs have made over these past 30 years have been marvelous to behold. In particular, compute-intensive software, such as electromagnetic (EM) simulation tools working with Maxwell’s equations, has benefitted from expanded memory and computing power over the years, whether these programs are working on planar or three-dimensional (3D) circuit problems.
Those working in this industry long enough will remember some of the early software tools as being little more than calculators. The development of SPICE software at the University of California at Berkeley in the 1970s and ’80s—along with the creation of commercial RF/microwave design tools by Les Besser (see Microwaves & RF, November 2011) and others during that timeframe—set the stage for what would become a healthy market for linear and nonlinear circuit and EM simulation tools, leveraging each new improvement in computer microprocessor capability with new sets of functions and easier-to-use graphical user interfaces (GUIs). Ironically, at one time, authors of many technical publications compared the plots of their simulated scattering (S) parameters to the results from a carefully calibrated microwave vector network analyzer (VNA). Now, it seems more often than not that many researchers are using the results from the software simulations to validate the accuracy of their laboratory measurements.
Modern software design and simulation tools truly are the accumulated knowledge of many design engineers who came before—not just their wisdom and insights into designing couplers, filters, amplifiers, and other circuits, but files with models that have proven successful and test results from actual circuits to fortify the software. There is simply no question that RF/microwave software is better than it has ever been, with more functionality, more models, and more features than before, to take advantage of personal computers (PCs) with considerably more processing power than dreamed of 30 years ago.
So why not count on these software design tools completely? Because this industry has been built by folks willing to take chances, by design engineers who didn’t always follow what came before, but chased their own creative thought processes to develop out-of-the-ordinary solutions to a design problem (such as a nontraditional circuit structure to couple energy from one point to another in a circuit). A proven efficiency enhancer, CAE software is a tremendous benefit to this industry. But it never hurts to walk away from the computer and try thinking “out of the box” now and then, just to see what wild ideas come. That special moment of realization can make it all worthwhile.