Field-Deployable System for the Measurement of Complex Permittivity of Improvised Explosives and Lossy Dielectric Materials

Field Representation Microwave Thermography Utilizing Lossy Microwave Design Materials

“…In (21), the parameter β th is called thermal retardation, a form factor that compensates measurement setup geometries etc. Once the thermal retardation is evaluated the time constant τ th can be obtained.…”

A Submersible Printed Sensor Based on a Monopole-Coupled Split Ring Resonator for Permittivity Characterization

“…In many areas of science and engineering, the ability to monitor and quantify the dielectric permittivity of materials using non-destructive methods with high sensitivity and precision is required. The measurement of permittivity is related to other characteristics of the material and can be used to determine changes in its density, concentration, composition, temperature, stress-strain tensor, among others [3,4,5,6,7,8]. For this reason, the measurement of this parameter is very important in many fields, some of which are agriculture [9,10], security [5], food quality [4], biology [11,12], among others.…”

“…The measurement of permittivity is related to other characteristics of the material and can be used to determine changes in its density, concentration, composition, temperature, stress-strain tensor, among others [3,4,5,6,7,8]. For this reason, the measurement of this parameter is very important in many fields, some of which are agriculture [9,10], security [5], food quality [4], biology [11,12], among others. For example, the permittivity of vegetable oils is measured and evaluated according to the variation of the temperature and it has been established in [13], that an increasing temperature increases the permittivity of vegetable oil.…”

“…These are all non-destructive methods. Another non-resonance but destructive method is the transmission and reflection method, because a portion of the material under test (MUT) has to be situated inside the transmission line, so particular dimensions are required to ensure a correct fit [2,5]. Due to the low cost of development, real-time monitoring, easy integration and easy miniaturization, resonance methods have generated great interest in recent years.…”

“…In the resonant perturbation methods, a cavity resonator is filled with the sample under test (SUT), and the shift in the resonance frequency and the change in the quality factor are measured. With a precise sample preparation, this method becomes the most precise one, but is just applicable over a narrow band, and besides, this method is considered destructive if the material must be damaged to perform the test [5,14,19]. On the other side, the resonator methods are non-destructive since the SUT can be considered as part of the resonator and the permittivity can be deduced from the displacement of the relative frequency of resonance, which has a relatively high precision and sensitivity [2,21,24,25,26,27].…”