Spiral-type transmission line with an Mn-Zn ferrite core

Spiral-type transmission-line devices using an Mn-Zn ferrite core were developed, which consisted of a spiral winding with a polyimide dielectric and a ground plane, an Mn-Zn ferrite pot core (TDK; PC-50). The devices exhibited 20-dB attenuation in a wideband frequency range, which was not only due to the high frequency loss of the ferrite but also due to the distributed constant circuit operation. To analyze the characteristics, a distributed constant circuit model was introduced considering magnetic coupling between different turns in the spiral winding.