A magnetic resonance imaging system for imaging an object, the system comprising: an imaging region arranged to receive the object; a generator of a Radio-Frequency, RF, signal having a wavelength; a static magnetic field source; a unit for forming a gradient magnetic field; a device for receiving RF signals; and a metamaterial device coupled to the Radio-Frequency, RF, signal, wherein the metamaterial device is positioned close to the device for receiving RF signals, the metamaterial device comprising: a plurality of extended conductors each having a respective length which satisfies a half-wave resonance condition at the wavelength of the RF signal in the metamaterial device, the metamaterial device being configured to locally increase the magnetic field strength of the RF signal at the wavelength, wherein the respective lengths of the plurality of extended conductors have an average value between 0.4 and 0.6 times the wavelength, wherein each of the plurality of extended conductors has a respective cross-sectional dimension and the respective cross-sectional dimensions have an average value between 0.00001 and 0.01 times the wavelength, wherein the plurality of extended conductors are positioned relative to each other at distances having an average value between 0.001 and 0.1 times the wavelength, wherein the extended conductors are manufactured from a non-magnetic metal, wherein the extended conductors of the plurality of extended conductors are isolated from each other, wherein at least part of the extended conductors of the metamaterial device is located inside a dielectric material, wherein the dielectric material has an average dielectric permittivity ε greater than 60. an imaging region arranged to receive the object; a generator of a Radio-Frequency, RF, signal having a wavelength; a static magnetic field source; a unit for forming a gradient magnetic field; a device for receiving RF signals; and a metamaterial device coupled to the Radio-Frequency, RF, signal, wherein the metamaterial device is positioned close to the device for receiving RF signals, the metamaterial device comprising: a plurality of extended conductors each having a respective length which satisfies a half-wave resonance condition at the wavelength of the RF signal in the metamaterial device, the metamaterial device being configured to locally increase the magnetic field strength of the RF signal at the wavelength, wherein the respective lengths of the plurality of extended conductors have an average value between 0.4 and 0.6 times the wavelength, wherein each of the plurality of extended conductors has a respective cross-sectional dimension and the respective cross-sectional dimensions have an average value between 0.00001 and 0.01 times the wavelength, wherein the plurality of extended conductors are positioned relative to each other at distances having an average value between 0.001 and 0.1 times the wavelength, wherein the extended conductors are manufactured from a non-magnetic metal, wherein the extended conductors of the plurality of extended conductors are isolated from each other, wherein at least part of the extended conductors of the metamaterial device is located inside a dielectric material, wherein the dielectric material has an average dielectric permittivity ε greater than 60. a plurality of extended conductors each having a respective length which satisfies a half-wave resonance condition at the wavelength of the RF signal in the metamaterial device, the metamaterial device being configured to locally increase the magnetic field strength of the RF signal at the wavelength, wherein the respective lengths of the plurality of extended conductors have an average value between 0.4 and 0.6 times the wavelength, wherein each of the plurality of extended conductors has a respective cross-sectional dimension and the respective cross-sectional dimensions have an average value between 0.00001 and 0.01 times the wavelength, wherein the plurality of extended conductors are positioned relative to each other at distances having an average value between 0.001 and 0.1 times the wavelength, wherein the extended conductors are manufactured from a non-magnetic metal, wherein the extended conductors of the plurality of extended conductors are isolated from each other, wherein at least part of the extended conductors of the metamaterial device is located inside a dielectric material, wherein the dielectric material has an average dielectric permittivity ε greater than 60.