“…Those devices were also used in industrial and military applications, such as satellite communications and radars, in the high-frequency band from several gigahertz to several tens of gigahertz (X band to K band) [4,5]. Technical trends included the fabrication of via-hole/PHS (plated heat sinks), MMIC (monolithic microwave IC), and efficient harmonic control, in addition to the microstructure of the devices [6,7].…”