Preliminary characterization of microwave backscattering of floating plastic

Abstract

Microwaves (MW) may offer advantages over optical techniques for remote monitoring of marine litter. However, no systematic studies are found in the literature about microwave sensing of floating plastics. In order to assess the potential, we carried out two types of experiments and analysis. In one scenario we measured and characterized the MW backscatter of different densities of typical plastic bottles and jerry cans, floating in a small pool of static water. The results show a significant increase of litter response with litter density, thus demonstrating that floating plastic affects the MW backscattering of the water surface. In the second scenario, we assembled a setup to resemble a synthetic aperture radar system: a small container filled with water and floating plastic was linearly translated under a fixed antenna operating in monostatic mode; we have successfully reconstructed the energy backscattering map of the target. This preliminary work demonstrates that floating macro plastics do present a MW signature that may be relevant for remote monitoring of this type of marine pollution.