Influence of skin depth on NMR coil impedance. Part II.

We present a theoretical description of the interaction between an NMR coil system and a lossy conducting sphere. The influence of the finite skin depth or RF penetration and the relatively large dielectric constant of biological samples on the sample-induced electrical impedance of the coil is treated explicitly. The results are shown to be in good agreement with experiment and reduce to the more traditional expression for the coil impedance of Hoult and Lauterbur (1979) in the low conductivity or small sample size limit.