Flexible active antenna arrays

Abstract

Complex and dynamic control of radiated fields are advantageous for flexible radio systems, which naturally move, roll, bend, twist, deform, and vibrate. Practical challenges hinder the proliferation of these antenna arrays. This work shows how using radio-frequency microchips reduces system component count, decreases mass to ~0.1 g cm−2, and increases functionality and mechanical flexibility. We develop a general platform for large scale flexible arrays and demonstrate two different 256-elements, 30 × 30 cm2 flexible arrays. By varying supply distribution methods and radiators we show how performance can be optimized for maximum power delivery or physical flexibility. The demonstrated systems conform to curved surfaces with radii of curvatures as low as 23 cm and wirelessly deliver ~ 80 mW of DC power to a 6.7 cm × 11 cm-receiver over one meter away. This paves the way towards the integration of smart arrays in flexible wearables and deployable lightweight airborne systems.

Frontiers in Flexible and Shape-Changing Arrays

“…If greater flexibility is required, discrete dielectric patches can be utilized as illustrated in Fig. 8(e), at a cost of mass and/or loss compared to air gap patches [70]. In higher frequency ranges, where the flexible substrates are thick enough to be a meaningful fraction of a wavelength, inkjet-printed antennas have been successfully demonstrated as shown in Fig.…”

“…A larger implementation of a continuously flexible phased array presented in a more streamlined design was demonstrated in [70] where the platform that was used in [82] was fitted with dielectric patch antennas instead of a single sheet. Fig.…”

“…The RFICs dissipate power and create heat which must be removed but the thin, light, flexible substrates generally have low thermal mass and thermal conductivity. The 256 element arrays shown in [70] use flexible copper strips as heatsinks attached to the back of the RFICs and convection for cooling. These copper strips are connected to the RFIC with thermal paste and attached to the flexible substrate with epoxy.…”

“…The electrical interface and integration level metrics capture some of the logistical challenges of deploying these array implementations. The ideal electrical interface is minimally intrusive, such as a small ribbon of flat flexible cables interfacing over a narrow section of a single side of the shapechanging array as found in [70], [72]. Less optimally, [43], [44], [68] require cables or connectors on multiple edges of their flexible substrate.…”

Flat‐Knit, Flexible, Textile Metasurfaces

“…Flexible metasurfaces can also help further reduce the weight of existing planar, rigid devices and improve their stowability, enabling a new class of lightweight, flexible, easily stowable, and deployable, large-aperture antennas [26][27][28][29][30] for applications such as long-range communications. Previous research efforts toward flexible metasurfaces, reflectarrays, and array antennas include devices printed, written, or deposited on flexible substrates, [31][32][33] "kirigami"-inspired, 3D printed reflectarrays, [34] "origami"-inspired, foldable, multisection reflectarrays, [28,30,35,36] complex, multi-layered, flexible phased arrays, [37,38] and textile-based metasurfaces and reflectarrays, including woven frequency-selective surfaces, [39,40] directwrite frequency-selective surfaces, [41] and embroidered, textile reflectarrays. [42][43][44] While work concerning textile metasurfaces, reflectarrays, and array antennas is a nascent field, far more extensive research on simpler, singular textile antennas and flexible, textile-based electronics has been carried out over the past few decades.…”