Yield monitoring whilst harvesting, in combination with a positioning system, is a fundamental
source of information for generating field yield maps. In this research, a capacitive
throughput sensor for potatoes and sugar beets has been tested. The principle of the sensor
is based on the fact that the dielectric constant of an air/material mixture between two
parallel plates increases with material volume concentration. A theoretical model for
a capacitive throughput sensor has been developed; the model incorporates all the most
important physical parameters that influence material throughput measurement. Two
basic relationships between the sensor electrical capacity and material throughput were
derived from the proposed model, a hyperbolic relationship and a linear relationship. The
method of presenting the measured material to the sensor was the most important factor
in explaining sensor behaviour. The theoretical considerations were confirmed by dynamic
laboratory experiments using potatoes and sugar beets.