## 5 Conclusions  
A resonant cavity-based Wireless Power Transfer (WPT) system intended for remote charging of a battery incorporated into the smart suit developed by our partners was thoroughly investigated and optimized. The WPT systems under study utilize a standard carbon steel closet as a metallic enclosure required to confine electromagnetic fields to the cavity interior. The proposed solution is cost-effective, as it does not require an expensive enclosure made of copper; however, it exhibits a lower power transfer efficiency than its copper counterparts with the same dimensions. Two printed antennas were fabricated and used to ensure power transfer from an RF generator to the receiver (an RF-DC converter) inside the closet. Due to the softness of the suit material, the precise antenna placement was difficult to ensure. This issue can be mitigated by making the WPT system's efficiency less sensitive to the receiver position within the closet. The results confirm the findings of our previous study, in which only full-wave analysis was carried out. Namely, the optimization results show that extending the design of the Tx antenna by introducing an additional conducting strip parallel to the dipole located a distance away results in wider regions with high electric field intensity. These strong fields, in turn, ensure sufficiently high power transfer efficiency (PTE) of the cavity-based WPT system for reliable charging of a battery incorporated into smart clothing placed inside the closet. Wider high PTE regions inside the closet are of utmost practical importance in smart suit charging, as this mitigates the sensitivity of the system's PTE and, therefore, the overall WPT system's efficiency to the Rx antenna position. The mechanism responsible for the increase in the high PTE region is explained based on the theoretical analysis of the interaction between the sub-models containing a dipole antenna and a conducting strip (director). It was found that the change in the phases of three waveguide modes (TE\({}_{01}\), TE\({}_{21}\) and TM\({}_{21}\)) ensuring the power transfer between the Tx and Rx ends may significantly extend the high PTE region. An exhaustive search-based optimization was performed to find the optimal antenna parameters, giving the widest high PTE region. Since the exhaustive search-based optimization requires exceedingly large amounts of CPU time when applied directly to the original WPT system's model, the model decomposition method was employed. Specifically, the WPT model was divided into three sub-models. For each sub-model, the individual generalized S parameters were computed using the full-wave simulator Ansys HFSS 2023 R1 for different sub-model parameter combinations and exported into files. Then, the WPT system's S parameters were computed using a custom MATLAB routine by combining the precomputed sub-model matrices. A substantial reduction in the CPU time was achieved because the sub-model parameter space dimensions are much smaller than that of the entire model, and the S matrix recombination requires just a few seconds per combination. The closet-based WPT system's PTE was calculated at different vertical and horizontal positions of the Rx antenna inside the closet to examine the effect of the antenna position on the system's performance. The simulated results were also experimentally verified. The comparison of calculated and measured PTE shows close agreement between the results. The shape of the theoretical curves obtained for different positions of the receiving antenna mostly agrees with the experimentally obtained ones. The highest measured PTE of the cavity-based WPT system (about 60%) was achieved when the receiving antenna was located halfway between the side walls of the closet. Some discrepancies between the measured and calculated results are attributable to the presence of coaxial cables and wires, which were considered in the simulation. Conceptualization, R.K. and D.P. ; methodology, R.K.; software, R.K.; validation, R.K., J.E. and S.T. ; formal analysis, D.P.