Microstrip moisture sensor based on microstrip patch antenna

Abstract

A miniaturized U-shape patch sensor (15 mm × 15 mm) was designed at dual resonating frequencies (f r ) 5.2 GHz and 6.8 GHz. The proposed design printed on FR4 material with a thickness of 1.676 mm and relative permittivity 4.4. To simulate the performances of the proposed design, the CST Microwave Studio (CST MWS) was used. The reflection coefficient of U-shape patch sensor was measured. Basmati rice was investigated, and bulk density was increased with increase of moisture content, hence varied from 554.3 to 591 kg/m 3 . It has the longest average rice length (L) 7.2 mm, average width (W) 1.61 mm, and L/W ratio 4.47. The percentage of moisture was varied from 10.71% to 21.87% calculated on a wet weight basis. The lowest mean relative error (MRE) determined between predicted moisture content (PMC) and actual moisture content (AMC) was 0.55% at dual frequencies.