Radio-transparent dipole antenna based on a metasurface cloak

Abstract

Antenna technology is at the basis of ubiquitous wireless communication systems and sensors. Radiation is typically sustained by conduction currents flowing around resonant metallic objects that are optimized to enhance efficiency and bandwidth. However, resonant conductors are prone to large scattering of impinging waves, leading to challenges in crowded antenna environments due to blockage and distortion. Metasurface cloaks have been explored in the quest of addressing this challenge by reducing antenna scattering. However, metasurface-based designs have so far shown limited performance in terms of bandwidth, footprint and overall scattering reduction. Here we introduce a different route towards radio-transparent antennas, in which the cloak itself acts as the radiating element, drastically reducing the overall footprint while enhancing scattering suppression and bandwidth, without sacrificing other relevant radiation metrics compared to conventional antennas. This technique opens opportunities for cloaking technology, with promising features for crowded wireless communication platforms and noninvasive sensing.

Polarization-Insensitive Metasurface Cloak for Dynamic Illusions with an Electromagnetic Transparent Window

“…For instance, a perfect stealth antenna radome should transmit the in-band waves and simultaneously reduce the probability of being detected by a hostile radar. Recently, some metasurface cloaks with the communication window have already been proposed to bring available camouflage strategies for practical applications. , For example, Sun et al presented a cross-wavelength cloak that can simultaneously enable microwave illusion and visible transparency, thus realizing the integration of stealth and communication functionalities . Alù et al proposed a radio-transparent dipole antenna, which utilized the cloak as an efficient radiator to eliminate undesired cross-coupling between the elements, enhancing the performance of scattering suppression and bandwidths .…”

“…38 Alùet al proposed a radio-transparent dipole antenna, which utilized the cloak as an efficient radiator to eliminate undesired crosscoupling between the elements, enhancing the performance of scattering suppression and bandwidths. 39 However, these achievements are generally passive, which cannot meet the requirement of applications in non-stationary external environments. In view of the above factors, it is highly desired to develop a reconfigurable and polarization-insensitive cloak with a communication window.…”

“…Recently, some metasurface cloaks with the communication window have already been proposed to bring available camouflage strategies for practical applications. , For example, Sun et al presented a cross-wavelength cloak that can simultaneously enable microwave illusion and visible transparency, thus realizing the integration of stealth and communication functionalities . Alù et al proposed a radio-transparent dipole antenna, which utilized the cloak as an efficient radiator to eliminate undesired cross-coupling between the elements, enhancing the performance of scattering suppression and bandwidths . However, these achievements are generally passive, which cannot meet the requirement of applications in non-stationary external environments.…”

Metasurface with Electrically Tunable Microwave Transmission Amplitude and Broadband High Optical Transparency

“…Metasurfaces are two-dimensional metamaterials consisting of periodic arrays of subwavelength artificial units that offer the advantages of ultrathin thickness, lightweight, design flexibility, and ease of fabrication. − In particular, metasurfaces have the ability to arbitrarily manipulate the electromagnetic wave amplitude, phase, frequency, and polarization state. Examples of metasurfaces include absorbers, − antennas, − polarization converters, , beam shapers, − holographic imaging, − and other interesting applications. − These conventional metasurfaces are mostly static; in other words, their electrical, magnetic, and magnetoelectric responses are fixed by design, and once manufactured, their functions cannot be tuned to meet the requirements of increasingly complex applications. Hence, tunable metasurfaces provide a versatile platform for the dynamic manipulation of electromagnetic waves. − Various developments have been made using lumped elements (e.g., varactors and PIN diodes), − actively controlled materials (e.g., graphene, − ferroelectric materials, liquid crystals, − and phase change materials − ), and mechanically tunable metasurfaces. − …”

Recent Progress in Reconfigurable and Intelligent Metasurfaces: A Comprehensive Review of Tuning Mechanisms, Hardware Designs, and Applications

“…In 2011, the generalized Snell's law was proposed, [12] and space-gradient metasurfaces were engineered to undergo abrupt phase change and manipulate EM waves by introducing a phase discontinuity at the interface between two media. Accordingly, metasurfaces have been used to realize a wide range of applications such as holographs, [13,14] anomalous reflection, [15][16][17][18] orbital angular momentum (OAM), [19][20][21][22][23] analog differentiator, [24] EM scattering, [25][26][27] metalens, [28][29][30][31][32][33][34][35][36][37] cloaking, [38][39][40] optical encryption, [41] quantum information, [42,43] and retroreflectors. [44,45] Historically, metasurfaces were designed to realize a singular function for a specific incident wave; therefore, they could not realize dynamic functionalities.…”