1,127 research outputs found
Experimental Synthetic Aperture Radar with Dynamic Metasurfaces
We investigate the use of a dynamic metasurface as the transmitting antenna
for a synthetic aperture radar (SAR) imaging system. The dynamic metasurface
consists of a one-dimensional microstrip waveguide with complementary electric
resonator (cELC) elements patterned into the upper conductor. Integrated into
each of the cELCs are two diodes that can be used to shift each cELC resonance
out of band with an applied voltage. The aperture is designed to operate at K
band frequencies (17.5 to 20.3 GHz), with a bandwidth of 2.8 GHz. We
experimentally demonstrate imaging with a fabricated metasurface aperture using
existing SAR modalities, showing image quality comparable to traditional
antennas. The agility of this aperture allows it to operate in spotlight and
stripmap SAR modes, as well as in a third modality inspired by computational
imaging strategies. We describe its operation in detail, demonstrate
high-quality imaging in both 2D and 3D, and examine various trade-offs
governing the integration of dynamic metasurfaces in future SAR imaging
platforms
Electromagnetic Absorbers Based on Frequency Selective Surfaces
Frequency Selective Surfaces (FSSs) are bidimensional
arrays of particles arranged in a periodic manner.
These surfaces can be lossless or lossy, depending on the
manufacturing process. They can be fabricated by using metallic or
controlled-resistance surface deposition. Lossy surfaces can be also
obtained through the integration of lumped components on a
metallic surface. The use of FSSs has fostered new research lines in
the design of electromagnetic absorbing surfaces, bringing
improvements both in terms of bandwidth/thickness ratio
maximization and in terms of customizability of the absorbing
bandwidth (narrowband, multi-band, wideband, ultra-wideband) for
specific applications. Artificial impedance surfaces (or HighImpedance
Surfaces, - HIS) are thin resonant cavities synthesized
by printing a periodic frequency selective surface on the top of a
grounded dielectric slab. By proper tailoring of the geometrical and
electrical properties of the FSS as well as the substrate, several
electrically-thin absorbing designs can be obtained. Ultranarrowband
absorbers with extremely stable angular behavior, often
addressed as metamaterial absorbers, can be realized by exploiting
only dielectric losses of commercial substrates. Narrowband,
wideband and ultra-wideband configurations are instead
implemented by also resorting to ohmic losses in a non-conductive
FSS. A thorough review of the available absorbers will be presented
together with multi-band and tunable design techniques.
Manufacturing processes and practical examples will be also
addressed, and the most interesting fields of application of the
presented structures will be described
Convergent communication, sensing and localization in 6g systems: An overview of technologies, opportunities and challenges
Herein, we focus on convergent 6G communication, localization and sensing systems by identifying key technology enablers, discussing their underlying challenges, implementation issues, and recommending potential solutions. Moreover, we discuss exciting new opportunities for integrated localization and sensing applications, which will disrupt traditional design principles and revolutionize the way we live, interact with our environment, and do business. Regarding potential enabling technologies, 6G will continue to develop towards even higher frequency ranges, wider bandwidths, and massive antenna arrays. In turn, this will enable sensing solutions with very fine range, Doppler, and angular resolutions, as well as localization to cm-level degree of accuracy. Besides, new materials, device types, and reconfigurable surfaces will allow network operators to reshape and control the electromagnetic response of the environment. At the same time, machine learning and artificial intelligence will leverage the unprecedented availability of data and computing resources to tackle the biggest and hardest problems in wireless communication systems. As a result, 6G will be truly intelligent wireless systems that will provide not only ubiquitous communication but also empower high accuracy localization and high-resolution sensing services. They will become the catalyst for this revolution by bringing about a unique new set of features and service capabilities, where localization and sensing will coexist with communication, continuously sharing the available resources in time, frequency, and space. This work concludes by highlighting foundational research challenges, as well as implications and opportunities related to privacy, security, and trust
Convergent Communication, Sensing and Localization in 6G Systems: An Overview of Technologies, Opportunities and Challenges
Herein, we focus on convergent 6G communication, localization and sensing systems by identifying key technology enablers, discussing their underlying challenges, implementation issues, and recommending potential solutions. Moreover, we discuss exciting new opportunities for integrated localization and sensing applications, which will disrupt traditional design principles and revolutionize the way we live, interact with our environment, and do business. Regarding potential enabling technologies, 6G will continue to develop towards even higher frequency ranges, wider bandwidths, and massive antenna arrays. In turn, this will enable sensing solutions with very fine range, Doppler, and angular resolutions, as well as localization to cm-level degree of accuracy. Besides, new materials, device types, and reconfigurable surfaces will allow network operators to reshape and control the electromagnetic response of the environment. At the same time, machine learning and artificial intelligence will leverage the unprecedented availability of data and computing resources to tackle the biggest and hardest problems in wireless communication systems. As a result, 6G will be truly intelligent wireless systems that will provide not only ubiquitous communication but also empower high accuracy localization and high-resolution sensing services. They will become the catalyst for this revolution by bringing about a unique new set of features and service capabilities, where localization and sensing will coexist with communication, continuously sharing the available resources in time, frequency, and space. This work concludes by highlighting foundational research challenges, as well as implications and opportunities related to privacy, security, and trust
- …