The design of radio frequency (RF) coils is of paramount importance to the quality and safety of Magnetic Resonance Imaging (MRI). Being the signal generator and detector of MRI, RF coils are required to generate a uniform excitation in the target during transmission and high signal-to-noise ratio (SNR) during reception. In the meantime, RF coils must not cause subject overheating in in-vivo human studies. This requires that RF energy deposited inside the human body and coupled to receivers should be minimized. By Shumin Wang and Hai Lu