  A first investigation into the use of microwaves for the non-destructive
testing for the presence of black heart cavities is presented. Additionally a
potato's complex permittivity data between 0.5 GHz to 20 GHz measured using a
coaxial sensor and the recipe for a potato phantom are also presented.
Electromagnetic finite-difference time-domain simulations of potatoes show that
changes to how microwaves propagate through a potato caused by a cavity can
produce measurable changes in S21 at the potato's surface of up to 26 dB.
Lab-based readings of the change in S21 caused by a phantom cavity submerged in
a potato phantom liquid confirms the results of the simulation, albeit at a
much reduced magnitude in the order of 0.1 dB.
