To measure the electromagnetic properties of steel fiber-reinforced concrete (SFRC) in the X-band, 1-port measurements were performed using a lens horn antenna in a free-space measurement system. Free-space 1-port calibration with translations of the position of the reflector regarding the characteristics of the focused beam lens horn antenna was applied. The intrinsic impedance and complex permittivity of the SFRC were obtained from the measured reflection characteristics. The steel fiber content increased and the electromagnetic properties of the SFRC gradually changed from a dielectric to a conductor, even in very low frequencies compared to the plasma frequencies of general metal, which are optical frequencies. This is considered to be the plasmon effect of the metallic structure formed by the steel fiber. This result is applicable for analyses of the electromagnetic phenomenon of large structures with fiber content.

Steel fiber is a material frequently used when contained in concrete because of its various architectural advantages, and it plays a role in increasing the electromagnetic shielding effectiveness (SE) of the building owing to its high conductivity. Thus, this study analyzed the SE of the steel fiber reinforced concrete (SFRC) according to the structural parameters of the steel fiber. The equivalent permittivity of concrete was extracted using the Jonscher model; The concrete was modeled using the electromagnetic simulation tool, and the electromagnetic properties were analyzed according to the orientation, number, and length of the steel fiber. Thus, depending on the structural parameters of the steel fiber, the causal relationship of the polarization of the incident wave, level of the SE, and resonance frequency was derived.