Think Outside the Band: Design and Miniaturization of Absorptive Filters

A teaching assistant once told me that, as microwave engineers, impedance matching is "what we do." We do much more than that, of course. But I think it is true that this is what most of our more complex tasks ultimately boil down to. To design an amplifier, you have to match the impedance of the transistor. To design an antenna, you have to match its radiation impedance. We do it by rote, without thinking, like a writer punctuating sentences. It is no wonder that the Smith chart-the classic graphical tool for analyzing and displaying an impedance match-has become our field's own personal totem.