A Microwave Sensing System Based on Transmitarray Antennas for Detecting Low-Density Contaminants in Food Packaged Products

A novel microwave sensing (MWS) system for detecting low-density contaminants in food packaged products is presented in this work. The proposed MWS system is featured by a pair of transmitarray antennas designed at 10 GHz with electrically reconfigurable unit cells. The focus spot of the transmitarray antennas can be scanned and focused at the desired positions along the horizontal or vertical direction in their near-field region. Compared with existing standard MWS systems with fixed waves, the proposed MWS system has a larger and more flexible near-field detection coverage. Moreover, the electric field is enhanced by the transmitarray, which contributes to a better detection. Then, we design a machine learning model, based on the proposed transmitarray antenna, to detect the different low-density contaminants in static oil-filled food jars. Experimental results demonstrate improved performance in the detection accuracy where 100% and 99% are observed with different scanning strategies with the proposed system, while less than 90% with the existing standard ones.