Ambiguous Influences Affecting Insertion Loss of Microwave Printed Circuit Boards [Application Notes]

Software design programs often assist RF/ microwave engineers in creating high-frequency printed circuit boards (PCBs). A multitude of commercial software tools are available, from electromagnetic (EM) simulation programs to circuit layout and complete system simulators. Both engineers and software tools try to forecast the effects of various circuit- and material-based parameters, but some factors may be overlooked or simply not well enough understood to be properly accounted for in a software simulation of a PCB design. This article intends to help RF/microwave PCB designers better understand the different influences affecting high-frequency PCB loss performance, such as copper roughness, solder mask, plated finishes, and circuit configurations, and how to more accurately predict their effects on final PCB insertion-loss (IL) performance.