Frequency-Domain Characterization of Plastic Litter in Aquatic Environments Using Microwave Sensing

In this study, the sensitivity of microwaves to plastic waste in the aquatic environment is analyzed through a laboratory experiment. A bistatic radar configuration is developed to observe plastic material deployed in a small tank filled with fresh water. The plastic is observed under different submersion and moisture conditions, in a broad range of frequencies and in both co- and cross-polarization. Experimental results indicate that at higher frequencies (> 4 GHz) the signal resulting from plastic can be distinguished from the reference calm water one. Both co- and cross-polarized radar configurations allow discriminating plastic from water surface; however, the cross-polar configuration calls for a lower amplitude signal. Plastic wetness conditions play a key role in radar observation performance, with wet plastic resulting in the best detectability.