AbstractThis paper presents a theoretical analysis method and basic characteristics of triplate spiral inductors. The analysis is based on low‐frequency band transmission line theory from which three different transmission line circuits are used to model the inductor; after obtaining the circuit impedances for different potential profiles, we consider the high‐frequency problem using a model in which the interline electric field couplings are simulated as lumped capacitances. Based on these techniques, it is possible to investigate the basic properties such as the inductances, self‐resonant frequencies and losses.The triplate inductors can be used as three‐dimensional hybrid IC elements in the UHF band (0.3 – 3 GHz) such as broadband matching circuits, various filters, and decoupling circuit for the power supply line.