Broadband radar invisibility with time-dependent metasurfaces

Abstract

Concealing objects from interrogation has been a primary objective since the integration of radars into surveillance systems. Metamaterial-based invisibility cloaking, which was considered a promising solution, did not yet succeed in delivering reliable performance against real radar systems, mainly due to its narrow operational bandwidth. Here we propose an approach, which addresses the issue from a signal-processing standpoint and, as a result, is capable of coping with the vast majority of unclassified radar systems by exploiting vulnerabilities in their design. In particular, we demonstrate complete concealment of a 0.25 square meter moving metal plate from an investigating radar system, operating in a broad frequency range approaching 20% bandwidth around the carrier of 1.5 GHz. The key element of the radar countermeasure is a temporally modulated coating. This auxiliary structure is designed to dynamically and controllably adjust the reflected phase of the impinging radar signal, which acquires a user-defined Doppler shift. A special case of interest is imposing a frequency shift that compensates for the real Doppler signatures originating from the motion of the target. In this case the radar will consider the target static, even though it is moving. As a result, the reflected echo will be discarded by the clutter removal filter, which is an inherent part of any modern radar system that is designed to operate in real conditions. This signal-processing loophole allows rendering the target invisible to the radar even though it scatters electromagnetic radiation.

Naked eye direction of arrival estimation with a Fresnel lens

“…While the previous sections concentrated on the ability to identify a single source (angular accuracy), distinguishing between several targets and even counting their number is highly important in radar applications, e.g. 1 , 46 , 47 . This capability is referred to as an angular resolution.…”

Compact High‐Gain Volumetric Phased Array Antenna with Genetically Designed Interelement Resonances for 5G Applications

“…While the current layout can be implemented by a manual shaping of metal wires, we exploited additive manufacturing techniques, which certainly have advantages in cases where complex 3D-shaped structures are involved. Recently, we masted several selective plastic and polymer metallization techniques, [7,[9][10][11][12][13] and an improved variation of one of those will be used hereinafter. A thiocarbamide gloss-forming agent was added to the electroplating routine.…”

“…Carefully designed surfaces (metasurfaces) can tailor the properties of transmitted and reflected waves. [7,[11][12][13] In contrast to phased arrays, metasurfaces utilize near-field coupling between elements. DOI: 10.1002/pssr.202200497 High-gain directive antennas are used to support point-to-point long-range wireless communication channels.…”

“…For example, tunable capacitance elements allow shifting resonant responses of individual elements, and as a result, either amplitude or phase switchable screens are achieved. [12,19,20] Fast-developing concepts of 5G communication protocols challenge hardware peripherals and motivate the development of new devices. [21] For example, reconfigurable antennas, aimed to maximize data rates, spectral efficiencies, and other parameters, can be affordable by smart devices with computational capabilities (e.g., smartphones).…”

Special scattering regimes for conical all-dielectric nanoparticles

“…This unique regime has already found a plethora of emerging applications, such as, e.g. sensing 78 , energy harvesting 79 , radar deception 80 , etc. To enhance scattering, it is generally believed that one needs to spectrally overlap the resonant frequencies of several QNMs scattering to different multipoles 37 .…”