Abstract
Permittivity sensing is commonly utilized in multiple fields for various applications. In this study, an enhanced RFID (Radio Frequency Identification) permittivity sensor system is designed. Additionally, we investigated the signal processing procedures in a stepwise manner to obtain the resultant graphs. For validation, a simplified system including a reader and a tag is tested. The reader in the system comprises a pulse generator and a pair of antennas connected to an oscilloscope, whereas the tag comprises an antenna and a delay line sensor. The pulse generator produces short pulses of less than 1 ns periodically, whereas the short-ended delay line on the tag acts as a sensor, wherein the delay time of the traversing wave is primarily associated with the relative permittivity of the material under test (MUT). We tested the system to derive an equation for the value of relative permittivity of the MUT using the measured signal. The system was calibrated by performing both unloaded and air tests to obtain measurement equations. Moreover, an additional test validated the water permittivity sensing, and the relative permittivity measured was 78.1. Considering the errors affecting the measurements, the measured relative permittivity of water concurs with the actual value.
Highlights
Sensors are commonly used to measure different properties of a material
This study investigated the feasibility of a chipless radio frequency identification (RFID) permittivity sensor
The pulse wave generated at the input port of the sensor in the tag antenna travels through the delay line within a certain time
Summary
Among the multiple types of sensing techniques, permittivity sensing is applied in various fields, including biomedicine, agriculture, architecture, and automobile manufacturing [1]–[4] Several methods, such as the transmission line method, resonant technique, open-ended coaxial probe method, timedomain reflectometry (TDR), and free-space method, are used to test the permittivity [5]–[8]. In applications such as safety and engine monitoring system, portable measuring devices that can collect information in real-time are highly preferred. The tag includes a sensor that translates the permittivity of the MUT into an electrical signal The receiver recognizes this signal and displays the result on a monitor. No amplifiers are included in the tested system
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