Many of Japan's infrastructures are more than 50 years old afterconstruction,11and their aging is expected to accelerate in the future.Therefore, the challenge is to in-12spect the deteriorated condition of those infrastructures.This study focuses on the use of13electromagnetic waves in NDT as an inspection method for infrastructure.One issue14with this method is that the device is not suitable for actual infrastructure inspections.15We constructed a portable reflection measurement system that utilizes sub-terahertz16waves among electromagnetic waves.Reflection measurementswere conducted on cor-17roded and uncorroded steel plates using this compact system.It may be possible to18identify samples using peak shift with a horn antenna. With a probe antenna, identifica-19tion is based on reflectance.