Deep Analysis of Patella caerulea Calcined Shells for Microwave Applications

This study investigates the potential application of Patella caerulea shells collected from the Iskenderun Bay as biomaterial in microwave radomes and examines the dielectric properties of shells calcined at 600-1200 °C. At the central frequency of 10 GHz, the real permittivity values for P600, P800, P1000 and P1200 are 3.2, 2.3, 2.4 and 2.5, respectively. The corresponding imaginary parts at 10 GHz are 0.82, 0.44, 0.52 and 0.56, reflecting temperature-dependent variations. The loss factor of shells, particularly at 2.5 GHz, indicates their potential for low-loss applications in communication, such as microwave laminate and radome applications. Moreover, these materials have been integrated to a traditional patch antenna to show feasibility in a microwave system as a substrate layer. At temperatures exceeding 800 °C, slight increase in the CaO peaks was observed in X-ray diffraction spectrum. The thermal gravimetric analysis and differential thermal analysis of shell powder reveal weight loss occurring in two distinct stages and minor endothermic peaks at 125°C and 275°C. The study highlights that microwave antenna radome materials are promising due to their high impedance matching and low-loss properties. This research contributes to the exploration of marine-sourced materials for economic and ecological benefits in the field of microwave technology.