The two-sheet capacitive Jaumann absorber

Many Jaumann absorber designs rely on purely resistive sheets spaced λ/4 apart, and the designs are based on the requirement that the voltage reflection coefficient and its derivatives vanish at the center frequency. The thickness of the absorber can be reduced and its bandwidth considerably expanded if the sheets are allowed to have capacitive reactances in addition to pure resistance. The bandwidth can be expanded even more by imposing different design criteria. We illustrate those advantages by invoking what we call a double-notch design process for a simple two-sheet absorber