Application of copper plates for frequency tuning of surface wired and wireless MRI coils

[Display omitted] •Quite easy method for frequency tuning of the surface RF coil to a higher frequency range.•No need to interfere into the electric circuit of the RF coil.•Enough to place RF shield on the conducting circuit of the surface RF coil.•The method can be applied for surface wired RF coils and wireless transmission line resonators. This study shows how a copper plate could be used for frequency tuning of surface wired and wireless MRI coils. For this purpose, it is proposed to place the copper plate directly on their conducting circuit. This leads to increase in the resonance frequency of coils. The effect is most perceptible if the copper plate is comparable in size to the conducting circuit of radiofrequency (RF) coil. The experimental work was performed on a 7.05 T MR scanner using surface MRI coils operating on different resonance frequencies: 1H (300 MHz), 31P (121 MHz), 23Na (79 MHz), 13C (75 MHz). Application of copper plate for frequency tuning of wireless multi-turn multi-gap transmission line resonator (MTMG-TLR) was considered for the first time. The proposed method can be claimed if the nominal variable inductance or capacitance is not enough for tuning the resonance frequency of the MRI coil to a higher frequency range.