A pneumatically tunable, conformal, and polarization-independent electromagnetic absorber

This research is focused on the design and realization of a low-cost conformal electromagnetic absorbing layer based on a composite of carbon nanotubes (CNTs) in polydimethylsiloxane (PDMS). It is experimentally demonstrated that the electromagnetic properties of the composite, i.e., its permittivity and loss tangent can be engineered. On that basis, composites with different concentrations of CNTs (and as a result different complex permittivities) are used for the design of a multi-layer absorber. In order to validate the design, a prototype of the absorber is fabricated and concept and the design are validated both numerically and experimentally. Experimental results show a measured absorption better than 96% at the central frequency of operation of the absorber. The proposed absorber benefits from a flexible shape that can be conformed to cover curved surfaces. Moreover, since the proposed absorber is initially in a semi-liquid state, it can be applied as a coating layer on almost any geometry. The absorber is waterproof and polarization independent. It is also shown that the operating frequency of the absorber can be pneumatically tuned.