Non-Destructive Testing for Black Heart Cavities in Potatoes with Microwave Radiation

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.