This paper presents the design, fabrication, and characterization of a self-foldable Active Origami Reflector Antenna (AORA) of parabolic form. Self-folding of the AORA is enabled by smooth uncreased folds composed of shape memory polymer (SMP) composites. Design methods for origami with smooth folds are applied to determine the shape and fold pattern of a planar sheet that can be folded to reach the parabolic antenna shape. A proof-of-concept prototype of the AORA is fabricated and self-folding of the AORA driven by thermal actuation of the SMP composite folds is demonstrated. The far-field electromagnetic (EM) characteristics of the AORA prototype are investigated through numerical simulations and experimental measurements in an anechoic chamber. A design-of-experiment study is conducted to investigate the effects of the antenna shape parameters on its EM characteristics such as far-field antenna gain and beamwidth, and to compare the performance of the AORA to that of equivalent smooth and faceted parabolic reflectors. Applications of the AORA include high-gain directional radio telescopes and satellite telecommunication.

Frequency selective surfaces (FSS) filter specific electromagnetic (EM) frequencies defined by the geometry and often fixed periodic spacing of a conductive element array. By embedding the FSS pattern into an origami structure, we expand the number of physical configurations and periodicities of the FSS, allowing for fold-driven frequency tuning. The goal of this work is to examine the folddependent polarization and frequency behavior of an origami-inspired FSS under normal incidence and provide physical insight into its performance. The FSS is tessellated with the Miura-ori pattern and uses resonant length metallic dipoles with orthogonal orientations for two primary modes of polarization. A driven dipole model with geometric morphologies, representative of the folding operations, provides physical insight into the observed behavior of the FSS. Full-wave simulations and experimental results demonstrate a shift in resonant frequency and transmissivity with folding, highlighting the potential of origami structures as an underlying mechanism to achieve fold-driven EM agility in FSSs.

The physical reconfiguration and deployment of a 2×2 corporate-fed microstrip patch antenna array is investigated. The origami-inspired antenna array reconfigures structurally using a Miura-ori fold pattern to deploy to/from a compact folded state from/to a flat state. The impact of folding on the electromagnetic performance is evaluated across a range of physical states to study the impact of physical reconfiguration. In particular, the input impedance and beamforming capabilities are used to characterize the performance as a function of the primary folding parameter. These performance metrics are impacted by a feed network that extends across the folds and the beamforming capabilities that are impacted by the changing element spacing and orientation. Results from simulation and a fabricated structure are provided for a 2.4 GHz design.

Filtering of electromagnetic signals is key for improved signal to noise ratios for a broad class of devices. However, maintaining filter performance in systems undergoing large changes in shape can be challenging, due to the interdependency between element geometry, orientation and lattice spacing. To address this challenge, an origami-based, reconfigurable spatial X-band filter with consistent frequency filtering is presented. Direct-write additive manufacturing is used to print metallic Archimedean spiral elements in a lattice on the substrate. Elements in the lattice couple to one another and this results in a frequency selective surface acting as a stop-band filter at a target frequency. The lattice is designed to maintain the filtered frequency through multiple fold angles. The combined design, modeling, fabrication, and experimental characterization results of this study provide a set of guidelines for future design of physically reconfigurable filters exhibiting sustained performance.

This work investigates and develops the physical reconfiguration and deployment of a previously designed 2×2 corporate-fed microstrip patch antenna array. The physical reconfiguration of the antenna is achieved using a Miura-ori fold pattern due to its utilization for deployment. Increasing the fold angle impacts the input impedance and beamforming capabilities by changing the element spacing and orientation. The previous design experienced a graceful degradation in electromagnetic performance as the fold angle increased. Further optimization led to a more robust and functional antenna array system. The antenna is enhanced by designing the array with circularly polarized patch elements. The use of circular polarization eliminates the need to study the polarization changes during intermediate folding states and enables pattern reconfigurability. The performance of the circularly polarized array is evaluated over a comprehensive range of angles to evaluate the impact of physical reconfiguration. Results from a simulated circularly polarized array are provided for a 3GHz design.

Recent studies demonstrate the benefit of integrating origami in many engineering applications, where computational methods facilitate the origami design process. An emerging concept utilizes origami design for physically and functionally flexible electromagnetic devices. However, coupled mechanical and electromagnetic design tools are needed to systematically navigate the complex spaces of fold topology and electromagnetic performance. In this article, we introduce topology optimization formulations that find origami fold-driven frequency selective surface designs possessing electromagnetic filtering properties at target frequencies. These formulations utilize a nonlinear mechanics analysis to simulate an origami folding process. A geometric mapping relates mechanically-relevant origami substrate properties and electromagnetically-relevant conductive element properties. Both gradient-based and genetic algorithm methods are used to find optimal origami crease patterns and folded configurations by optimizing fold stiffness and force distributions over a prescribed potential fold line network. Using nonlinear manifold learning techniques, we demonstrate the isolated nature of optimal design candidates in the design space and the complex interplay of fold topology and fold path selection through initial perturbation from the flat state. Collectively, this study provides an initial framework to design novel EM origami structures and also provides important insights on the complex nature of the design space, which can be leveraged to refine future tool development.