  We investigated inductive power transfer (IPT) through a rectangular slab of
saltwater. Our inductively-coupled transmitters and receivers were made from
loop-gap resonators (LGRs) having resonant frequencies near 100 MHz. Electric
fields are confined within the narrow gaps of the LGRs making it possible to
strongly suppress the power dissipation associated with electric fields in a
conductive medium. Therefore, the power transfer efficiency in our system was
limited by magnetic field dissipation in the conducting medium. We measured the
power transfer efficiency as a function of both the conductivity of the water
and the resonant frequency of the LGRs. We also present an equivalent circuit
model that can be used to model IPT through a conductive medium. Finally, we
show that using dividers to partition the saltwater volume provides another
means of enhancing power transfer efficiency.
