In order to do theoretically research suppressing induced current of field-to-line coupling by ferrite magnetic rings

by the transmission line theory as well as material characteristics of ferrite magnetic rings

we established a transmission line model with a distributed source of coaxial shielded cable with magnetic rings-ground circuit in frequency domain

thus the induced sheath current can be acquired conveniently for different terminal loads of cable. Additionally

we analyzed the mechanism of suppressing induced sheath current by ferrite magnetic rings

.and discussed the relationship between suppression effect and material characteristics. The results show that the ferrite magnetic rings can be utilized to effectively suppress induced current for different terminal loads of cable; when the difference between inner and outer radius of a magnetic ring is same

the smaller the inner radius

the better the suppressing effect; when the inner radius is the same

the larger the outer radius

the better the suppressing effect; when the shape of a magnetic ring is the same

the larger the permeability

the better the suppressing effect. Measured results demonstrate that the proposed model is correct. The research results can provide a theoretical basis for type selection of magnetic rings and save experimental expenditures.