In this study we present the design and realization of a tunable dual band wireless power transfer (TDB-WPT) coupled resonator system. The frequency response of the tunable band can be controlled using a surface-mounted varactor. The transmitter (Tx) and the receiver (Rx) circuits are symmetric. The top layer contains a feed line with an impedance of 50 Ω. Two identical half rings defected ground structures (HR-DGSs) are loaded on the bottom using a varactor diode. We propose a solution for restricted WPT systems working at a single band application according to the operating frequency. The effects of geometry, orientation, relative distance, and misalignments on the coupling coefficients were studied. To validate the simulation results, the proposed TDB-WPT system was fabricated and tested. The system occupied a space of 40 mm×40 mm. It can deliver power to the receiver with an average coupling efficiency of 98% at the tuned band from 817 to 1018 MHz and an efficiency of 95% at a fixed band of 1.6 GHz at a significant transmission distance of 22 mm. The results of the measurements accorded well with those of an equivalent model and the simulation.