Ultimate signal-to-noise-ratio of surface and body antennas for magnetic resonance imaging

Approximating the human body by a homogeneous half-space or cylinder the el ectromagnetic fields of surface antennas or wholebody antennas for magnetic resonance imaging (MRI) can analytically be calculated, Using these expres sions the signal-to-noise ratio (SNR) of a general magnetic resonance detec ting antenna ran be predicted. We show how the optimum magnetic resonance a ntenna must look like to achieve the maximum SMR, which will also be presen ted. Finally, we apply the derived formulas to special antenna geometries l ike the single-and the double-loop coil, the magnetic dipole, and the "bird cage" resonator.