100 IEEE ANTENNAS & PROPAGATION MAGAZINE AUGUST 2017 TESTING OURSELVES Levent Sevgi MATLAB-based propagation tool called plate graphical user interface (PlateGUI), which calculates and shows electromagnetic (EM) fields inside a parallel-plate waveguide using different analytical and numerical models, was developed and is discussed in this article. PlateGUI can be used in graduate-level courses that deal with guided-wave the- ory and computational electromagnet- ics (CEM). A NEW SIMULATION TOOL EM problems are complex in nature, but wave theory is well established with Max- well equations. Solution strategies may be grouped into three areas: analytical modeling, numerical simulations, and measurements. Measurement in EM is time consuming, expensive, and, in most cases, extremely difficult to do. A limited number of analytical solutions is available for only a few highly idealized problems, so numerical simulation is the only means for almost all real-life EM engineering problems. This is why modeling and sim- ulation in EM has made significant prog- ress for the last couple of decades [1]–[4]. The philosophy is to keep it as simple as possible so it can be used as a basic CEM tool and supply simple MATLAB codes so even beginners can use them. Propagation inside a parallel-plate wave- guide with perfectly electrical conducting boundaries in two dimensions is one of the most simple and widely used struc- tures to achieve these tasks. In the “Education Corner” column in the April 2016 issue of IEEE Antennas and Propagation Magazine [5], Maas- kant and Rosen revisited this problem and presented an analytical problem- solving approach with educational value for EM theory. In their article, they also shared their MATLAB code. This problem has been examined in several studies before [6]–[19], some of which were published in this magazine. The classic paper for the analytical ray- mode and hybrid formulations was first presented by Kamel and Felsen in [7]. Visualizations of these hybrid ray-mode techniques were discussed in [12], and a free MATLAB package was introduced. Algorithms and codes for the numerical solution of this problem using different models were also presented—e.g., finite difference time domain (FDTD) in [15], the parabolic equation (PE) method in [16] and [17], the method of moments (MoM) in [18], and so forth. There are also several books that have become clas- sics in the presentation of this problem (e.g., [20]–[26]). Propagation inside a parallel-plate waveguide is an interesting EM prob- lem where both analytical and numeri- cal models can be comparatively tested against each other. ■ First, the Green’s function solution is exact but requires an infinite num- ber of mode summations. This is a numerical challenge, especially in the near vicinity of the line or Gaussian source. The modes are categorized into two groups: propagating modes and evanescent modes. The number of propagating modes depends on the frequency and the plate width. A tilted directional antenna can also be located inside and modeled in terms of modes, but modal excitation coef- ficients become complex in this case. This is another numerical challenge, A MATLAB-Based Virtual Tool for Simulations of Wave Propagation Inside a Parallel-Plate Waveguide Gökhan Apaydin and Levent Sevgi Digital Object Identifier 10.1109/MAP.2017.2707324 Date of publication: 4 August 2017 1045-9243/17©2017IEEE EDITOR’S NOTE In this issue’s “Testing Ourselves” column, a MATLAB-based education tool that can directly be used for both undergraduate- and graduate-level guided wave theory and computational electromagnetics types courses is introduced. The tool can be downloaded from http://leventsevgi.net/index.php?page=emvirtualtools. The authors are also willing to share this upon request. A