## 1 Introduction  
Over the last several decades, Wireless Sensor Networks (WNSs) have been an active field of research due to the multitude of useful functions they can perform in various areas of human activity, including construction, medicine, biology, health control systems, etc. [1]. Owing to recent advances in microelectronics and materials, a wide variety of miniature and powerful sensors have become available. This enables wearable sensor nodes to efficiently and reliably monitor users' health state, e.g., smart clothing incorporating a number of dedicated sensors. The smart clothing can perform various functions, including continuous measurement of body temperature and spinal posture, and gait monitoring during exercise to protect the user (a patient) from falling and becoming injured [2, 3]. It might be beneficial for persons suffering from various impairments and disabilities as it may reduce the risk of serious injuries, thereby increasing the quality of life [4]. While capable of performing their intended tasks autonomously and establishing communication links with other WSN nodes,the batteries powering the electronic components need periodic recharging or replacement. The recharging necessitates sockets and jack plugs, which affect the integrity of the suit structure and increase the risk of electric shock or fire when used in adverse conditions, such as increased humidity. Untethering these devices would considerably increase the user's comfort and reduce the risk of injuries due to malfunctioning clothing components [5]. The present study aims to evaluate the feasibility of a simple-to-use, and cost-effective remote powering system for charging a battery incorporated into the smart clothing (smart suit) recently developed by our partners [6]. The most suitable candidate for smart suit charging is resonant cavity-based WPT systems constructed by deploying a metallic chamber enclosing the workspace, which effectively becomes a resonant cavity. Since the EM field is confined to a finite region, no power is wasted due to path loss, resulting in higher PTEs. This allows reliable remote charging of home appliances, toys, gadgets, etc., placed inside the enclosure when their batteries become depleted or during the idle period, for example, overnight, so as not to expose the users to strong EM fields [7]. In fact, this study extends our previous research on the WPT system utilizing a carbon steel closet [8], which was confined to full-wave simulations only. In [8], different antenna (probe) designs, including dipole antennas, reflector-backed dipole antennas, and dipole antennas with both reflectors and an additional conducting strip (Yagi-like antennas), were examined. The Yagi-like antenna was found to extend the region of the closet's interior, where the PTE is high due to a strong electric field. However, no theoretical analysis was carried out to investigate the mechanisms responsible for such a WPT system's behavior, and experimental verification was needed. Thus, the primary objective of the present study is to find the cause of the increase in the high PTE region size and validate the simulation results via direct measurements of the received power performed in our faculty's laboratory. A standard carbon steel closet was chosen due to its availability in the mass market and relatively low cost. Alternatively, designing an efficient WPT system utilizing such common furniture elements would be attractive as it would obviate the need for constructing tailor-made room-scale enclosures, which necessitate quite a large quantity of copper and lead to less economical cost (it is more cost-effective while being slightly less efficient). The Inductive Power Transfer (IPT) method is a viable alternative to the cavity-based method [9]. Its impressive power transfer capacity allows quick remote charging. Recent studies have shown that the IPT can ensure maximally achievable power transfer efficiency (PTE) of up to 96.1% at an output power level of 20 kW [10].