Researcher(s)
- Jai Thacker, Engineering Undecided, University of Delaware
Faculty Mentor(s)
- Mark Mirotznik, Electrical and Computer Engineering, University of Delaware
Abstract
Frequency Selective Surfaces (FSS) are structures designed to selectively reflect, transmit, or absorb specific electromagnetic frequency bands. Traditionally, FSS are fabricated in two-dimensional lattices, limiting their application to flat surfaces. However, integrating FSS onto three-dimensional curved surfaces introduces geometric distortion that alters frequency selection. This study explores a novel approach to designing and manufacturing FSS suitable for non-planar, hemispherical radome applications.
Using conductive KA802 silver ink and a Fibonacci lattice to maintain a relatively constant distance between elements, an FSS was 3D printed using a nScrypt 3Dn-300 printer. The printed lattice was radially compressed by an estimated constant radial stretch from forming. COMSOL simulations confirmed that cross-shaped elements could be optimized to target a frequency of ~24.8 GHz. The FSS was formed over a metal dome, cured, and tested. Experimental results demonstrated that the FSS successfully filtered the desired frequency band with a ±1–2 GHz tolerance and maintained effective transmittance across rotation angles from 0° to 40° in each direction. This method presents a low-cost, customizable alternative to traditional 3D FSS fabrication for applications such as stealth technology and radome design.
To improve the precision of the formed FSS by more precisely accounting for distortion during forming, a test lattice was printed on Tailored Universal Feedstock for Forming (TuFF). The printed TuFF was formed into a spherical cap mold under pressure, then heated to cure. After cooling, the TuFF was removed from the mold and scanned using GOM’s ARGUS optical measurement system. The resulting positional data was imported into MATLAB to calculate geodesic stretch. This stretch data can be used to modify the original 2D lattice design, allowing the final printed pattern to conform to the dome shape while maintaining its intended electromagnetic properties.