Microstrip antennas for dielectric property measurement

The measurement of the dielectric properties of materials is of great interest in a variety of applications including measurement of the moisture, fat, salt, or sugar content of grains and food products, measurement of human tissues or artificial phantom materials used to simulate them, and many other scientific and commercial applications. Conventional methods of measuring these properties include coaxial measuring probes or cylindrical capacitive cells. The commercial equipment available for this purpose is generally too expensive to be used "in-line" and may be too fragile for many applications in harsh conditions. This paper describes microstrip antenna designs for the determination of dielectric properties. These antennas are designed for durability in extreme conditions and utilize a change of impedance when in direct or near contact to the sample to determine the dielectric properties.