Design of Filtering Cable Using Coupled Suspended Circuit With Dumbbell-shaped Defected Conductor Layer and Capacitors

This paper presents a filtering cable designed to control electromagnetic interference (EMI) by enclosing the power line with a coupled suspended circuit (CSC), which consists of a defected conductor layer (DCL) and surface-mounted capacitors. An equivalent circuit model for the filtering cable is developed, considering the transfer of current distribution from the DCL to an equivalent microstrip filter and extracting the circuit model of its discontinuity modules. The filtering cable achieves interference suppression exceeding 11 dB at 21.49 MHz with a capacitance of 1.36 nF for a single dumbbell-shaped defected structure (35 mm length on a transmission dielectric diameter of 24.3 mm), and 15.8 dB at 39.52 MHz with a capacitance of 400 pF. Furthermore, for a dumbbell-shaped defected structure length of 600 mm and a capacitance of 9.82 nF, the proposed filtering cable achieves interference suppression exceeding 5.98 dB at 2.23 MHz for a single resonator and 9.26 dB at 2.27 MHz for two cascaded resonators. Simulation and measurement results demonstrate the effective EMI suppression achieved by the proposed filtering cable, which can be further adjusted by modifying the areas of the dumbbell-shaped defected structure, the capacitors, and the cascading of resonators.