Advantages of ferromagnetic nanoparticle composites in microwave absorbers

Composites with nanosize ferromagnetic particles can be useful in microwave absorbers, since nanoparticles exhibit distinct magnetic properties compared to bulk materials. This paper examines theoretically the properties of composites with nanoparticles, the key material parameters, and the characteristics of a single-layer absorber made from a nanoparticle composite. In such an absorber, high magnetic losses over a wide frequency range induce a series of strong and wide absorption peaks at increasing frequencies. By using metallic (iron and cobalt) nanoparticles, absorbers with relatively low volume fraction of metallic inclusions can be made. The paper compares the characteristics of nanocomposite absorbers to those of common dielectric or ferromagnetic absorbers and identifies the potential advantages of nanocomposite absorbers. Because nanocomposite absorbers combine advantages of both dielectric and ferromagnetic absorbers and have significantly better characteristics, they could become essential for production of microwave and millimeter-wave absorbers.