A new planar microwave sensor for fat-measuring of meat based on SRR and periodic EBG structures

In this paper, we present a novel microwave sensor for sensing the fat of the meat with high sensitivity. We developed the sensor based on a bent transmission line (TL) and connected it to a split ring resonator (SRR). The gaps in the SRR make hot spots. The material under test (MUT) is placed on the hot spot to increase sensitivity. The sensor is surrounded by electromagnetic bandgap (EBG) elements in the final structure to enhance the Q -factor and save the electric field inside of the sensor. The full-wave simulation resonated with this sensor at triple frequencies of 3.4, 4.08, and 4.55 GHz. Additionally, the proposed EBG unit cell covers 2.4-5 GHz. So, it can make an electromagnetic shield for all resonances, and the final sensor shows dual-band characteristics at 3.48 and 4.67 GHz. The sensor is used to recognize the fat ratio in various meat samples. After Full-wave analysis, the equivalent circuit is extracted and modeled with the aid of an advanced design system (ADS). Next, the relation between the frequency shift of S21 nulls and fat percentages is calculated based on a proposed closed-form formula. In the end, comparing full-wave analysis, experimental results, and the equivalent circuit model shows perfect matching.