Additively Manufactured Aperture-Based FSS

Frequency selective surfaces (FSSs) are arrays of patch- or aperture-based elements with specific high frequency reflective and/or transmissive properties. The specific FSS response of a given design is dictated by the element dimensions and spacing relative to adjacent elements (collectively referred to as the unit cell), along with the substrate (and superstrate if applicable) properties. As it relates to sensing, the FSS response may be affected by environmental (e.g., temperature) or structural (e.g., strain) changes. To this end, FSS-based sensors have been considered in recent years for a myriad of sensing applications including structural health monitoring (SHM). Concurrent to this, the growth of additive manufacturing (AM) technologies has opened the door for in-situ printing of FSS-based sensors. To this end, this work studies the potential for Fused Deposition Modeling (FDM) type AM-fabricated FSS-based sensors. Of particular interest is the effect of the reduced electrical conductivity (common to currently available conductive FDM filaments) on the performance and repeatability of FDM-printed sensors. Results from this work show that aperture-based FSS designs maintain a resonant response when printed with a reduced-conductivity material, whereas patch-based designs no longer provide FSS functionality. In addition, the results of a measurement study on a set of five additive manufactured FSS (AM-FSS) sensors show good agreement between the simulations and measurements and a high level of measurement repeatability. For these reasons, aperture-based FSS sensors fabricated via the FDM-AM process using a reduced conductivity filament are a viable option for aperture-based FSS fabrication and sensing applications.