Measuring apparatus and method for determining a dielectric property, in particular moisture and/or density, in a product

Measuring apparatus for determining at least one dielectric property of a tobacco, cotton or other fibrous product, comprising:

• a device for generating a first high frequency wave;
• a measuring volume in which a product may be arranged;
• and
• a circuit device comprising:
• a measuring capacitor including first and second electrodes and a measuring volume located between the electrodes, wherein the first high frequency wave is applied to one of the electrodes to generate a high frequency field in the measuring capacitor influenced by a product arranged in the measuring volume of the measuring apparatus, wherein a second high frequency wave is produced at the other of the electrodes in dependence on the high frequency field;
• and
• a measuring device having an input coupled to the second high frequency wave to measuring variables of the second high frequency wave, wherein the circuit device is substantially non-resonant at the frequency of the high frequency field, the variables are based on the propagation of the second high-frequency wave, the measuring device operates to determine two mutually independent measurable variables which are dependent on the amplitude and phase of the second high-frequency wave, and the measuring device including a digital processing device, the measuring device samples the second high frequency wave with a sampling frequency higher than the frequency of the second high frequency wave by a factor of n, wherein n is a positive integer, and the digital processing device separately multiplies n sampled measurements over a period of the second high frequency wave by corresponding sine and cosine values and separately adds up the sine and cosine products.