Enhanced wireless power transfer system using integrated RF amplification

• Three-coil WPT with RF gain achieves stable power transfer up to 13 cm. • The integrated RF amplifier increases received output power by 42 %. • System efficiency improves by 36 % compared to a two-coil baseline. • The resonant design reduces mid-range power loss by 28 %. • The difference between simulation and experiment remains within 5 %. This paper focuses on the concept of wireless power transfer, a technology that allows power to be transmitted over a certain distance without wires. In this paper, we focused on the power support to the implanted biomedical devices, where supplying power using wires is challenging. It can also be implemented on various low powered electronic devices to deliver power efficiently. This study presents an optimized WPT system that enhances power transmission efficiency by integrating a novel three-coil design and an advanced RF amplification approach. Our proposed system operates within the radio frequency (RF) range, initially at 3 MHz, unlike conventional designs, this model integrates an oscillator with an RF amplifier directly into the coil, eliminating the need for separate power amplification and impedance matching network while improving signal strength and power delivery. The suggested method provides consistent power transfers up to 13 cm, exceeding typical two-coil systems. Experimental results show a maximum efficiency of 69 % at 7 cm for a two-coil system and 71 % at 13 cm for a three-coil arrangement. RF amplification boosts received output power by 42 %, while overall system efficiency improves by 36 %. Resonant tuning minimizes midrange power loss by 28 %, allowing for consistent performance across long distances. Circuit simulations were carried out using Multisim, MATLAB, and the CST Studio Suite. The proposed design operates safely under SAR limitations (<1 × 10⁻⁶ W/kg), making it ideal for biomedical implants, mobile device charging, and tiny electronics. This paper proposes a feasible and scalable engineering solution for efficient mid-range WPT applications.