Overview

This Special Issue, titled "RF, Microwave, and Millimeter Wave Devices and Circuits and Their Applications", presents a comprehensive overview of recent innovations in the design of high-frequency systems and of their multidisciplinary applications. The selected contributions span a wide array of domains-from power amplifiers, mixers, and phase shifters to advanced antenna arrays and metamaterial-inspired filters-demonstrating how the latest breakthroughs in circuit topology, device architecture, and packaging techniques are enabling the creation of high-performance systems at frequencies ranging from only a few to tens of gigahertz. We hope that this Special Issue will serve as both a valuable reference and a source of inspiration for engineers, researchers, and industry practitioners working at the frontier of RF, microwave, and millimeter wave technologies.