Wireless Ice Detection and Monitoring using Flexible UHF RFID Tags

Abstract

Owing to its low relative permittivity, very few microwave sensors have been developed for monitoring ice deposition. This paper presents the first use of UHF RFID tags for wireless RF ice sensing applications. Despite its low permittivity, the existence of ice as a superstrate on a planar ultra-thin dipole antenna can lower the resonance frequency of the antenna significantly. The RFID tags, having a measured unloaded range of 9.4 m, were evaluated for remotely detecting the formation of ice in various scenarios and up to 10~m from the reader, as well as monitoring the ice thawing, based on the Relative Signal Strength (RSS) in a phase-free approach. Unlike conventional RSS-based sensing approaches where the tag's read-range is reduced as the RSS decreases in response to the stimulant, the ice superstrate improves the impedance matching of the tags, maintaining a 10 m loaded read-range with over 12 dB ice-sensitivity, in an echoic multi-path environment. The long range and high sensitivity show that UHF RFID is a promising method of detecting and monitoring ice formation and thawing in future smart cities.

Toward the Optimal Antenna-Based Wireless Sensing Strategy: An Ice Sensing Case Study

“…For example, in renewable wind power farms, ice formation on wind turbines can reduce their power output by up to 30% over a year [3]. Recently, several solutions towards ice detection have been realized using Radio Frequency (RF) resonator [4], [5] or antenna-based solutions [4], [6], [7], making it a prime case study for comparing antennas in a dielectric sensing application.…”

“…Ice sensing is a prime case-study for RF-based sensors [6], [26]; ice is a low-permittivity and nearly lossless dielectric. While radar-based ice-sounding is a well-defined application of antenna arrays [2], it focuses on thick ice sheets.…”

“…Recently, microwave two-port resonators were proposed as ice and frost sensors [5], [26], surpassing other visual and optical methods. As resonators require active sampling circuitry, passive RFID tags were investigated for wireless ice detection [6]. We then investigated a 2.4 GHz wire-type antenna as an ice sensor, observing a correlation between the antenna's gain degradation and ice thickness [7]; aperture-type patch antenna sensors were also proposed based on gain measurements at 2.4 GHz [4], and based on S 11 measurements at 4 GHz [27].…”

Complex-Impedance Dipole Antennas as RFID-Enabled Ice Monitors

“…Monitoring the formation of ice and its water content or thawing process is of great interest for various applications. For example, detecting the formation of ice in smart cities can be utilized to prevent water pipes for bursting in winter [5], as well as avoiding slips and workplace injuries [6]. Furthermore, identifying the composition of snow basins, i.e.…”

“…A two-port RF resonator were proposed for as ice formation and thawing detection [8]. In [5], we investigated the performance of a robust conformable RFID tag, [3], as a wireless ice detection sensor [5], demonstrating an RSS change over 10 dB in the presence of ice. Nevertheless, detailed analysis of the antenna's impedance was not performed.…”