Dielectric and microwave absorption properties of sunflower and marigold: a comparative analysis

This article reports for first time, a comparative dielectric properties study of two dried flower biomasses (Sunflower and Marigold), with a prime focus on higher frequency behavior and analysis of reflection loss (RL) profiles for microwave applications. In this current investigation, the microwave absorption properties of two dried flower biomasses were prepared using a simple drying process. Microstructural study revealed unique canal and ribs cage structure in Sunflower and a highly porous flower-like structure along with agglomerated microspheres in Marigold biomass. Spectroscopic studies confirmed the presence of various functional groups and chemical constituents of both biomasses. The average dielectric constant and loss tangent vales of Sunflower and Marigold are found to be 2.61, 0.21 and 3.52, 0.23, respectively, using N5222B PNA Network Analyser. This variation in dielectric properties can be attributed to difference in their microstructure, carbon content, chemical constituents, and functional groups in naturally available biomasses. The reflection loss profiles were studied for both biomasses using CST Microwave Studio Simulator and a comparative analysis has done with wood biomass. Reflection loss profile of Sunflower was −18.80 dB with Effective Absorption Bandwidth (EAB) 5.38 GHz for 6 mm thickness and 7 mm shows highest EAB of 11.45 GHz which covers 82% of K-band. The reflection loss profile of Marigold shows −15.98 dB at 22.72 GHz frequency with EAB of 7.07 for 3 mm thickness.