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

Abstract

Moisture Content determination inside the grains is essential for grain processing activities including harvesting, storing, inspecting, and transporting. In this paper, microstrip and metamaterial embedded patch sensors were developed to determine the moisture content and mean relative error (MRE) of rice, wheat, and pulse. The sensors were simulated in HFSS, prototypes were fabricated and the measurement was done using VNA and anechoic chamber. The Microstrip sensor was operating at a frequency of 5.2 GHz and the metamaterial-embedded sensor was operating at 4.5 GHz. Calibration equations were obtained by using the values of reflection coefficients and moisture content ranging from 11.76% to 25%. For analyzing the efficacy of designed sensors, predicted moisture content (PMC) and actual moisture content (AMC) have been compared and the lowest mean relative error has been determined. The analysis shows that the metamaterial embedded sensor has better sensitivity and accuracy than the microstrip sensor. The lowest mean relative error in moisture prediction for metamaterial sensor was 1.07% for rice, 1.13% for wheat, and 1.47% for pulse respectively. A comparison of the proposed metamaterial embedded sensor with earlier designed sensor in literature was also presented in this work and it was found that the proposed sensor had more accuracy and sensitivity than earlier designs.