Abstract
With the advent of the Internet of things, 5G wireless communication, and smart city applications, demand for a new form of radio frequency (RF) electronics has risen, one that can be mounted or integrated on non‐conformal objects, is mass manufacturable at lower costs, and is optically transparent to maintain the aesthetics of the environment where deployed. This new breed of electronics can be realized through printing technologies, which are capable of manufacturing diverse designs on flexible substrates via large‐scale and high‐volume printing techniques at lower costs. However, the major challenge for printed electronics is the preparation of conductive inks with performance comparable to their bulk metal counterparts. This review summarizes the recent developments in printable transparent and conductive materials (TCMs), inks, and methods for optically transparent RF passives. In addition, techniques to enhance the conductivity of the TCMs are presented. Moreover, it covers several design examples of optically transparent RF passives, such as antennas, microwave absorbers, and frequency selective surfaces. Furthermore, many challenges and potential solutions are discussed in terms of the TCMs, inks, and printing technologies needed for the realization of such designs. Finally, some future trends in the area of transparent RF electronics and PE are discussed.
Innovative ideas in materials and designs for transparent radio frequency (RF) electronics enable the promising potential in the Internet of things and the fifth‐generation of wireless technologies. This review essentially covers the work conducted to date in this domain through printing technologies, including the introduction of various printing techniques, printable transparent materials, as well as printed transparent RF designs.