Explore a 20-minute conference talk from the MFEM Workshop 2022 focusing on OpenParEM2D, a free and open-source 2D electromagnetic simulator for guided waves and transmission lines. Delve into the capabilities and methodology of this GPLv3-licensed project, presented by independent software developer Brian Young. Gain insights into the motivation behind OpenParEM2D, its workflow for 2D ports, and sample results, including an accuracy example using a partially-filled waveguide. Discover the challenges faced in implementing the project with MFEM, such as handling 3D vectors in 2D and complex numbers. Learn about the steep learning curve associated with the project and its open-source nature. The presentation concludes with acknowledgments and is part of the LLNL-led MFEM (Modular Finite Element Methods) project, which provides high-order mathematical calculations for large-scale scientific simulations.