An Antenna-Based Permittivity Sensor for Liquid and Solid Characterization With a Dedicated Uplink Band and Provision for LTE Communication

This article presents a microstrip patch antenna-based permittivity sensor that can be used to characterize a wide range of liquids as well as solids. This is the first antenna-based sensor that can characterize both liquids and solids. The sensor can measure solid permittivity values from 1 to 13 and liquid permittivity values from 1 to 80. There are two separate sensing regions for liquids and solids with two different frequency bands used for characterization. There is also a dedicated uplink channel centered at 710 MHz for transmitting the sensed information wirelessly via the frequency division duplex (FDD) LTE Band 12 (698.2–716.2 MHz) or time division duplex (TDD) LTE Band 44 (703–803 MHz). This uplink channel enables the sensor to be a part of wireless sensor networks (WSNs). When not in use as a sensor, the antenna-based system can be utilized for dual-band and dual-linearly polarized communication within the 710-MHz LTE band as well as the FDD LTE Band 1 (2110–2170 MHz). This makes the system even more versatile. The solids and liquids can be removed with ease, thereby reducing the wait time between consecutive measurements. The sensor achieves a minimum sensitivity of 0.2% for both liquids and solids, which is at par with existing antenna-based sensors. Based on the different solid and liquid permittivity measurements performed, the maximum error in permittivity is found to be 3.18%, which is less than most antenna-based sensors in the literature.