  In this paper, secondary ferrite cores and resonant structures have been used
for field enhancement. The tissue was placed between the double square source
coil and the secondary ferrite core. Resonant coils were added which aided in
modulating the electric field in the tissue. The field distribution in the
tissue was measured using electromagnetic simulations and ex-vivo measurements
with tissue. Calculations involve the use of finite element analysis (Ansoft
HFSS) to represent the electrical properties of the physical structure. The
setup was compared to a conventional design in which the secondary ferrite
cores were absent. It was found that the induced electric field could be
increased by 122%, when ferrite cores were placed below the tissue at 450 kHz
source frequency. The induced electric field was found to be localized in the
tissue, verified using ex-vivo experiments. This preliminary study maybe
further extended to establish the verified proposed concept with different
complicated body parts modelled using the software and in-vivo experiments as
required to obtain the desired induced field.
