Abstract
A microstrip transmission line on an ungrounded copper base plane that is electrically isolated from a surrounding ground plane has two characteristic impedances that depend on the resistance between the grounded and ungrounded sections of the copper base plane. The achievable contrast depends on the geometry of the transmission line and the ungrounded copper plane. This paper investigated the characteristics of such dual-impedance transmission lines using electromagnetic modeling and fabricated and characterized transmission lines with systematically varying dimensions. And, it achieved a contrast between the two transmission line characteristic impedances by a factor of up to 2.3.
