Soil moisture remote sensing using SIW cavity based metamaterial perfect absorber

Abstract

Continuous and accurate sensing of water content in soil is an essential and useful measure in the agriculture industry. Traditional sensors developed to perform this task suffer from limited lifetime and also need to be calibrated regularly. Further, maintenance, support, and deployment of these sensors in remote environments provide additional challenges to the use of conventional soil moisture sensors. In this paper, a metamaterial perfect absorber (MPA) based soil moisture sensor is introduced. The ability of MPAs to absorb electromagnetic signals with near 100% efficiency facilitates the design of highly accurate and low-profile radio frequency passive sensors. MPA based sensor can be fabricated from highly durable materials and can therefore be made more resilient than traditional sensors. High resolution sensing is achieved through the creation of physical channels in the substrate integrated waveguide (SIW) cavity. The proposed sensor does not require connection for both electromagnetic signals or for adding a testing sample. Importantly, an external power supply is not needed, making the MPA based sensor the perfect solution for remote and passive sensing in modern agriculture. The proposed MPA based sensor has three absorption bands due to the various resonance modes of the SIW cavity. By changing the soil moisture level, the absorption peak shifts by 10 MHz, 23.3 MHz, and 60 MHz, which is correlated with the water content percentage at the first, second and third absorption bands, respectively. Finally, a $$6 \times 6$$ 6 × 6 cell array with a total size of $$312 \,\hbox {mm} \times 312 \,\hbox {mm}$$ 312 mm × 312 mm has been fabricated and tested. A strong correlation between measurement and simulation results validates the design procedure.

A polarization‐insensitive metamaterial absorber for moisture‐sensing applications of agriculture products

“…Moisture content is the most important factor in choosing the optimal time for harvesting and secure storage conditions in agriculture. 16 The proposed absorber qualities are being investigated for almond kernel moisture detection. Absorber-based sensing, which allows for noninvasive sensing without the need for electrical contact, is a promising method for remote sensing.…”

“…The amount of moisture present is often used as a measure of the quality of a product and is taken into account when determining the optimal collection and storage methods. Moisture content is the most important factor in choosing the optimal time for harvesting and secure storage conditions in agriculture 16 . The proposed absorber qualities are being investigated for almond kernel moisture detection.…”

Dual-Band X-Shaped Absorber Design for Sensor Applications

“…In practical applications, they are expected to have physical properties such as ease of manufacture, compactness, reusability, low cost, and electrical properties such as high sensitivity and quality factor. Many absorber designs of various types and specifications that can meet the principal requirements of the sensor applications have been reported in the literature [9][10][11][12][13][14][15][16][17][18][19][20]. In most of these studies, SRRs have been used as the primary absorbing structure, allowing high selectivity and quality factors due to their inherent resonant characteristic [10][11][12][13][14][15][16].…”

“…On the other hand, flower-shaped surrounded with the circular ring in [17] and swastika-shaped resonators in [18] have been considered absorbing elements for sensor applications. Similarly, microstructure metamaterial and substrate integrated waveguide cavity resonators have been employed in [19] and [20], respectively. This study proposes a novel compact absorber design based on an XSR for the S-band frequency region and investigates its sensor performance.…”

Microstrip and Metamaterial Embedded Patch Antenna Sensors for Determination of Moisture in Rice, Wheat, and Pulse Grains

“…10 Metamaterial-based sensors are currently experiencing substantial advances, with a degree of performance that can detect material information. [12][13][14][15][16][17][18][19][20][21] A large number of researchers in this field are becoming interested in metamaterials due to their exceptional electrical and magnetic properties, which have a variety of applications including absorption, sensing, polarization rotation, perfect lenses, source shifting and imaging, etc. [22][23][24][25][26][27] These sensors have certain unique qualities, including a simple design, ease of fabrication, low cost, high-quality factor and sensitivity, and reliability.…”