Microwave Behavior of Absorbing Materials With Spirulina Coated With Pure Iron and Design a Black Body for <inline-formula> <tex-math notation="LaTeX">$W$ </tex-math> </inline-formula>-Band

Abstract

Nanocomposites consisting of fine particles of spirulina coated with pure iron are able to change the dielectric permittivity and the magnetic permeability. The spirulina coated with pure iron is introduced as a kind of absorbing material, whose dielectric permittivity is $\sim 4-0.5j$ and the magnetic permeability is $\simeq 2.7-0.35j$ . The physical explanation of the fact that the spirulina structures contribute to the electromagnetic characteristics in W-band (75–110 GHz) is analyzed by the theory of the electrically small bifilar helix antenna. In addition, a black body is designed and fabricated. The emissivity of the black body is above 0.994 for both the TE and TM polarizations in the whole W-band, which meets the demanding of the remote sensing of the atmosphere.