A low-cost microwave moisture meter was built with offthe-
shelf components, calibrated and tested in the laboratory
and in the field at different peanut buying points in the U.S.
Fig. 4 shows the microwave moisture meter and the polycarbonate
peanut sample holder. The moisture meter, operating
at 5.8 GHz, uses the same design and measurement principle
shown in Fig. 3. The unshelled peanut sample was placed
in the sample holder between two high-gain patch antennas.
Step-by-step software was developed to guide the user
through the measurement procedure. The measurement required
less than a second from the time the peanut pods were
poured into the sample holder to provide, simultaneously,
peanut pod moisture and density, and peanut kernel moisture
content. Peanut pod bulk density and moisture content were
determined directly from measured dielectric properties by
using (1) and (4). For in-shell kernel moisture content, laboratory
calibrations provided the following equations for kernels