Because the degree of change in the dielectric constant with the change in moisture content decreases with increasing frequency , the difference in the dielectric constants of a parallel-plate capacitor
, holding wheat samples between the plates, measured at the two frequencies (1 MHz and 5 MHz) should be a good estimator of moisture content.
The capacitance of the microstrip parallel-plate capacitor
is determined by its area.
The trick is that the tactile sensor mat functions based on the principle of a parallel-plate capacitor
. Instead of plates, two textile components are employed, which form sensor cells arranged in a matrix.
Sensors are calibrated using a homogenous electrical field, which is produced by a large 1.5x1.5m parallel-plate capacitor
with 0.5m between the plates.
Taking a parallel-plate capacitor
, for example, the capacitance of the capacitor, [C.sub.0], is:
In the equation for the capacitance of a parallel-plate capacitor
, C = [[epsilon].sub.0][[epsilon].sub.r]A/t, it is the relative dielectric constant, [[epsilon].sub.r], that is varied in a BST capacitor, and can be typically varied by a 2:1 ratio or greater.
Most think of a pair of metal planes as a parallel-plate capacitor
. Thereby, the function of planes should be to provide the "plane capacitance" that helps maintain voltage stability.
Since the sensor is intended to measure a vertical component of electric field, it can be calibrated using a homogeneous electric field, which is produced by large parallel-plate capacitor
. Sensor and signal conditioning circuit is located in the middle of two plates parallel to them.
, which is composed of a series of microstrip meandered-line inductors, parallel-plate capacitors
, and interdigital capacitors.
are formed from two conductive plates separated by a dielectric with capacitance:
Figure 5 shows the extraction of capacitance parameters of [C.sub.p] versus [l.sub.p] with fixed W, using an equivalent series RLC circuit model fitted with the [S.sub.ll]-response of parallel-plate capacitors
. The full wave software package HFSS was used for the circuit simulation.