Flexible Transparent Antennas: Advancements, Challenges, and Prospects

Abstract

Optically transparent electronic devices have attracted enormous interests in recent years. The development of transparent electronics emerges a lot of new industrial applications in variety of fields, such as displays, glasses, solar panels, satellite communications, terrestrial communications, integrated circuits, and sensors where optical transparency is required for unobtrusive placement of electronic devices on the surface. Over the last couple of years, there have been notable advancements in the development of transparent wireless electronics due to the emerge of new materials and fabrication technologies. Among transparent electronic devices, transparent antennas attract tremendous interests due to their widespread applications in healthcare industry, security sector, defence, sports, smart city, internet of things (IoTs) and many more. Many of these applications require antennas that are concurrently transparent and flexible. A transparent and flexible antenna can be easily integrated with displays, windows, solar cells and optoelectronic modules, thus, reducing the space in the integrated circuits. However, still the development of flexible-transparent electronics is associated with some challenges which continue to impede the progress of this emerging field. Among them are the contradictory relationship between the electrical conductivity and optical transparency of the transparent conductors, costly and complex processing of the transparent materials and unavailability of the appropriate materials. In this paper, we discuss current advancements in the development of flexible transparent antennas, including potential applications, various enabling materials and manufacturing approaches, technical hurdles, as well as prospects.

Recent Advances in Multi-Material 3D Printing of Functional Ceramic Devices

“…Recently, the fabrication method and dielectric characteristics of the ceramic/polymer composite filaments for FDM of microwave devices (e.g., filters, antennas, and capacitors) have been widely investigated [ 154 , 155 , 156 , 157 , 193 ]. Castro et al [ 194 ] formulated two types of ceramic/polymer composite filament using polydimethylsiloxane (PDMS, which is a common substrate material for stretchable electronic devices [ 242 ], such as transparent antennas [ 243 ], field-effect transistors [ 244 ], photodetectors [ 245 ], and energy harvesters [ 246 ], because of its thermal stability, high optical transparency, and capability of attaining designer functionalities via surface modification and bulk property tailoring) reinforced by NdTi0 3 and MgCaTi0 2 fillers with volume loading up to 25%. After determining the microwave dielectric properties of the two types of ceramic/polymer composite filament, the authors demonstrated flexible microstrip antennas via an nScrypt 3Dn Tabletop printer coupling FDM and DIW.…”

Optically Transparent and Mechanically Flexible Coplanar Waveguide-fed Wideband Antenna Based on Sub-micron Thick Micro-metallic Meshes

“…Transparent antennas are visibly transparent devices that can transmit and receive electromagnetic (EM) signals. Since NASA proposed the first optically transparent microstrip patch antenna in 1997 [1], transparent antennas have experienced great development in the past two decades [2][3][4]. Because of the see-through feature, transparent antennas can be integrated onto solar panels, satellite, windscreens of automobiles, displays, windows, and so on [2][3][4], whose intrinsic performances are maintained without much degradation by the antennas.…”

“…Since NASA proposed the first optically transparent microstrip patch antenna in 1997 [1], transparent antennas have experienced great development in the past two decades [2][3][4]. Because of the see-through feature, transparent antennas can be integrated onto solar panels, satellite, windscreens of automobiles, displays, windows, and so on [2][3][4], whose intrinsic performances are maintained without much degradation by the antennas. Mechanical flexibility will endow transparent antennas with broader application scenarios, e.g., attachment onto curved surfaces and wearable devices, which however has not been investigated extensively [2,3].…”

Study of Gallium-Doped Zinc Oxide Thin Films Processed by Atomic Layer Deposition and RF Magnetron Sputtering for Transparent Antenna Applications

“…Additional access points and signal repeaters embedded into the existing infrastructure help mitigate these issues through embedding transparent antennas into the windows by means of metallic meshes , /nanowires or transparent conductive oxides (TCOs). ,, The present article demonstrates the first TCO-based transparent antenna processed entirely by ALD. Optically transparent antennas based on both AZO and GZO have been previously demonstrated (comprehensive reviews on TCO-based antennas here ,, ). AZO antennas were fabricated to operate at 11 and 45 GHz, and a GZO antenna was fabricated to operate at 2.4 GHz.…”