## 4 Conclusions  
According to the literature review, the eddy current method (EC) and the magnetic MFL methods are irreplaceable for assessing objects a few centimeters apart (like rebar in reinforced concrete RC structures). Other methods operating in this range (radiography or ultrasounds) have severe limitations in testing RC structures. The EC and MFL methods share similar principles and can be utilized for comparable tasks. A vital advantage of the magnetic method is its ability to employ strong excitation through permanent magnets, resulting in a significantly greater effective range. Experiments show that the MFL method enables effective identification in the typical range of concrete cover thicknesses (or higher). The effective range of the EC method depends on transducer size, used excitation frequency, quality of the transducer, and many other factors. However, experiments prove that the effective range of such transducers is usually limited to a few centimeters. (Figures 24 and 27). Therefore, the MFL method is preferable for testing RC structures. Figure 27: Results of steel class identification derived from both methods across all transducers. On the other hand, the EC method offers significantly better spatial resolution, making it effective for detecting small changes, such as a 2 mm diameter variation. However, it is challenging to construct an EC transducer capable of covering the entire typical range of concrete cover thicknesses within its optimal range. The MFL method offers better average identification in the whole range of measurements (depending on the EC transducer size and tested parameter, this difference can exceed 10%). However, if the EC transducer works in the optimal range (usually low concrete cover thickness), the obtained results can be significantly better than those of MFL (usually 3-10%). The EC method may be more effective than MFL when the concrete cover thickness is low, and variations in the value of the h parameter are low. Employing a set of EC transducers of varying sizes would be beneficial for achieving comprehensive identification. The higher effectiveness of the MFL method also comes from other facts. The magnetic method can utilize offsets for identification, which was quite beneficial during the research. In the case of the EC method, the offset is always equal to 0. Moreover, magnetic systems and transducers are generally more straightforward and cost-effective. They also allow for area measurements. In conclusion, the research suggests that the magnetic MFL method is more effective for identifying typical reinforced concrete structures. Small eddy current (EC) transducers, like the T5, demonstrate superior performance at low concrete cover thicknesses, achieving up to 5-10% better identification than larger transducers, such as the T25. Conversely, larger transducers tend to perform better (also by 5-10%) when the concrete cover thickness is greater. When averaging typical ranges of concrete cover thicknesses, larger transducers generally perform better than their smaller counterparts. Project management and administration, P.K.F. ; concept of the magnetic method, P.K.F. ; concept of the presented methodology, and algorithms, P.K.F. ; concept of the paper, P.K.F. ; software development (measuring system), P.K.F. ; software development (identification), P.K.F. ; hardware development, P.K.F. ; experiments and measurements, P.K.F. ; data curation, P.K.F., P.M., M.M. and T.S. ; formal analysis, P.K.F. ; investigation, P.K.F. ; resources, P.K.F. ; visualization, P.K.F. ; writing--original draft preparation, P.K.F. ; writing--review and extensive editing, P.K.F., P.M., M.M. and T.S. ; contribution of the authors in %: P.K.F.--80%, P.M.--9%, M.M.--9%, T.S.--2%. All authors have read and agreed to the published version of the manuscript.