Materials, Methods & Technologies, Volume 14, 2020

Rezumat: In this paper, we consider the characterization of microwave absorbers, including foam and rubber absorbing samples and coatings, composite absorbers with nanoparticle inclusions, meta-absorbers and gradient-carbon absorbers. Today, the development of new generation of effective absorbers is a big challenge because they are very promising materials for applications in the modern microwave 5G communication systems and antennas, where a reliable suppression of parasitically excited spurious fields must be achieved. The difficulties for characterization of such materials relate to the fact that they may have simultaneously as dielectric properties (usually big permittivity and dielectric losses), as well as expressed magnetic properties (non-zero permeability and big magnetic losses) and additionally – an increased conductivity. Therefore, the accurate determination of the full set of parameters can help the users to perform better design of microwave devices with incorporated absorbers and chemists and technology engineers to control the content, properties and applied technology of absorber materials. The paper presents and compares different measurement methods, models for extraction of the dielectric and magnetic parameters and conductivity and includes a lot of comparative results for a variety of absorbers. A new simple waveguide method has been presented for characterization of thin nano-composite absorbers with reliable separation of the equivalent dielectric and magnetic parameters.