Dielectric sensor

A method for obtaining a measure of the amount of anisotropy of an electrical property in a dielectric material specimen about a selected test point in a surface of the specimen, the electrical property being considered over directions in a measurement plane substantially parallel to the specimen surface at the test point, the method comprising the following steps:

• applying a time-varying electric field in at least two directions in a neighborhood of the test point;
• obtaining, during a first measurement time interval, a first signal proportional to the cosine of twice the angle in the measurement plane from a selected reference direction to the direction of electrical property maximum, the selected reference direction being any direction in the measurement plane;
• obtaining, during a second measurement time interval, a second signal proportional to the sine of twice the angle in the measurement plane from the selected reference direction to the direction of electrical property maximum;
• and
• processing the first and second signals to obtain the measure of the amount of anisotropy, the measure being independent of the selected reference direction.