A method of modeling RF properties of multilayered polymer host – metal nanoparticle guest composite films, using the transmission matrix method (TMM) model is presented. This is an alternate, pattern-less, dielectric approach to frequency selective surface electromagnetic interference shielding.
Origami devices have the ability to spatially reconfigure between 2D and 3D states through folding motions. The precise mapping of origami presents a novel method to spatially tune radio frequency (RF) devices, including adaptive antennas, sensors, reflectors, and frequency selective surfaces (FSSs). While conventional RF FSSs are designed based upon a planar distribution of conductive elements, this leaves the large design space of the out of plane dimension underutilized. We investigated this design regime through the computational study of four FSS origami tessellations with conductive dipoles. The dipole patterns showed increased resonance shift with decreased separation distances, with the separation in the direction orthogonal to the dipole orientations having a more significant effect. The coupling mechanisms between dipole neighbours were evaluated by comparing surface charge densities, which revealed the gain and loss of coupling as the dipoles moved in and out of alignment via folding. Collectively, these results provide a basis of origami FSS designs for experimental study and motivates the development of computational tools to systematically predict optimal fold patterns for targeted frequency response and directionality.
Origami structures morph between 2D and 3D conformations along predetermined fold lines that efficiently program the form, function and mobility of the structure. The transfer of origami concepts to engineering design shows potential for many applications including solar array packaging, tunable antennae, and deployable sensing platforms. However, the enormity of the design space and the complex relationship between origami-based geometries and engineering metrics places a severe limitation on design strategies based on intuition. This motivates the development of design tools based on optimization to identify optimal fold patterns for geometric and functional objectives. The present work proposes a topology optimization method using mechanical analysis to distribute fold line properties within a reference crease pattern to achieve a target actuation. By increasing the fold stiffness, unnecessary folds are effectively removed from the design solution, which allows fundamental topologies for actuation to be identified. A series of increasingly refined reference grids were analyzed and several actuating mechanisms were predicted. The fold stiffness optimization was then followed by a node position optimization, which determined that only two of the predicted topologies were fundamental and the solutions from higher density grids were variants or networks of these building blocks. This two-step optimization approach provides a valuable check of the grid dependency of the design and offers an important step toward systematic incorporation of origami design concepts into new, novel and reconfigurable engineering devices.