Wireless power transfer (WPT) continues to be popular in today's world because it is used in situations where the use of cables is difficult, dangerous, or restrictive. In WPT, electrical energy is transmitted over the air by magnetic connections instead of cables. In this paper, WPT system designs were made with 10 kHz and 20 kHz operating frequencies, 3.3 kW output power, and 50 cm x 50 cm size. The effects of the frequency on the WPT system were analyzed with the designs made for two separate frequencies. The WPT circuits were established in the MATLAB/Simulink program. The coil design of the WPT systems was made in ANSYS (R) Maxwell 3D. The critical air gap values of the 10 kHz and 20 kHz designs were determined as 15 cm and 17 cm, respectively. In this study, the efficiency of the WPT system was obtained as 88.79% at 15 cm air gap for 10 kHz and 92.74% at 17 cm air gap for 20 kHz. Wireless power transfer systems in different frequency bands at the same power were compared in terms of efficiency, loss, cost, and electromagnetic field distribution. In addition, the effects of WPT systems on human health were examined according to IEEE and ICNIRP standards.