13 - Origami-inspired 4D tunable RF and wireless structures and modules

Abstract

The chapter presents state-of-the-art techniques to realize origami-inspired radio frequency (RF) structures using four-dimensional (4D) printing technologies that exhibit unprecedented continuous-range wideband tunability characteristics. Traditionally, these structures were mostly realized on paper-based substrates that are prone to absorb moisture and tear, and feature high dielectric losses. Moreover, these structures required manual cutting and folding of the paper substrate, making it laborious and harder to replicate. 4D-printed origami-inspired RF structures are realized by first three-dimensional (3D) printing extremely complex origami structures using novel 3D-printed flexible materials, thereby making them durable, strong, and highly repeatable. Next, the RF structures are inkjet-printed on the 3D-printed origami structure to realize wideband, continuous-range tunability. These structures can be used to realize a wide range of tunable RF structures such as multilayer tunable metamaterials, reconfigurable antennas, wireless sensors, and dielectric reflectors. The chapter is organized as follows: First, a brief overview of additive manufacturing technologies such as inkjet printing and 3D printing along with origami-inspired RF structures will be presented. Next, a detailed description of one of the most fundamental origami structures, that is Miura-Ori tessellation, and its mathematical modeling, would be given. This work uses frequency selective surfaces (FSSs) to establish a one-to-one relationship between origami kinematics and corresponding RF characteristics. The basic operating and design principles are presented followed by a proof-of-concept state-of-the-art origami-inspired 3D/4D RF structure (Miura-FSS). Lastly, the chapter gives two unique techniques to realize Miura-FSS structures on cellulose and 3D-printed substrates using additive manufacturing technologies along with an in-detail discussion about their RF behavior with change in origami kinematics. Various techniques to realize a robust actuation mechanism are also presented that would facilitate a continuous range tunability for the origami RF structure.