This Special Issue of IEEE Microwave and Wireless Components Letters (MWCL) represents the second year that we include selected papers from the IEEE Microwave Theory and Techniques Society (MTT-S) International Microwave Symposium (IMS). The IEEE MTT-S IMS is the MTT Society’s flagship conference and the world’s largest meeting on microwave technology. This year, it is to be held in Denver, CO, USA, June 19–24, 2022.