Wideband Absorber Characterization Using Coaxial Airline and Electromagnetic Simulation

Portland State University

With the increase in popularity of electronic devices especially the wireless devices, microwave absorber becomes more essential to reduce electromagnetic interference. A deep understanding of electromagnetic properties namely electric permittivity and magnetic permeability is required in order to fabricate, test and use microwave absorber. In this study, we focused on developing a procedure to parameterize material electromagnetic properties. We first extract material properties by placing samples inside an airline and taking measurements of scattering parameters matrix with a vector network analyzer. Air-line is the preferred transmission line medium since the traveling wave inside the airline is both TEM and confined. The extraction process is verified with a full-wave EM solver. With the extracted material properties, we then simulate absorber performance by mimicking the naval research laboratory arch setup. Radar cross section is used instead of a full 3-D model to reduce complexity and computing resources. Finally, the reflectivity measurement the absorber is performed and compared with simulation results. All measurements were taken inside an anechoic chamber to reduce multiple reflections between interfaces. We have performed our analysis process for MR21, a commercially available microwave absorber and our results agree with their published datasheet. In future, we would like to use this process to analyze recently developed absorber such as Magnetically loaded flocked carbon fiber absorber (MLF-CF).