Design and Validation of a Microstrip Log-Periodic Feedline-Based Filter for Microwave Imaging of Rebar

The attenuation characteristics exhibited by structural materials are of significant importance in a wide range of engineering applications, as they directly impact the performance and longevity of these materials. This study introduces a new methodology for analyzing spatial variations in attenuation in reinforced cement concrete (RCC) cylindrical specimens using a log-periodic feedline (LPF)-based ring filter. The study centers around a cylindrical specimen divided into three distinct segments: a base section made entirely of cement, a middle section comprised of cement and iron reinforcement bars, and a top section consisting solely of iron reinforcement bars. Attenuation measurements were conducted at different heights by rotating the cylindrical specimen at 10°, employing a signal generator (SG) and analyzer setup. The results highlight the influence of various specimen sections on signal attenuation by demonstrating that attenuation rises. This methodology offers a flexible approach that can be applied to more general material science and structural engineering research, in addition to providing insightful information about the behavior of RCC materials.