I. Introduction
A compact WPT system is proposed earlier in [1] using resonating etched grounds called defected ground structure (DGS) resonators. By back to back coupling of two DGS resonators, the system transforms to a wireless power transfer system (WPT) [1]. Later, the freedom in optimizing the KQ (coupling × quality-factor)-products, which offered by the DGS [2], allows the designer to optimize WPT performance depending on their target applications. By these theories, dual-band DGS-WPT system is proposed by cascading the DGS and fed the system using a single fed line that also acts as different capacitors at different frequencies [3].