Dielectric measurements of mangoes from 0.5GHz to 20GHz using a custom open-ended coaxial probe

In this paper, we present the calibration procedure of an open-ended coaxial probe for the non-invasive dielectric characterization of biological samples at microwave frequencies. Custom broadband probes are characterized using an in-house rational function model enabling direct VNA calibration at the coaxial aperture plane. The custom coaxial probes are then used to characterize the dielectric properties of healthy and infected mangos (Xanthomonas campestris bacteria) over the frequency band ranging from 500MHz to 20GHz. A relative difference, in the mean epsilon (over 8 samples) values between the good and infected mangos, of 30% and 40% is found for the real and imaginary part of the permittivity respectively over the band 0.5-5GHz.