In this letter, we propose a magnet-less non-reciprocal isolating system based on time-varying metasurfaces. Two parallel metasurfaces, one for frequency up-conversion and down-conversion by the same amount, are used realizing region of space where incident waves from opposite directions experience an Doppler shift. As result, any device within becomes sensitive to illumination direction, exhibiting different scattering response thus breaking reciprocity. Very importantly, thanks shift...

The development of the next generation wireless systems is bringing renewed attention to physical layer communication link. Indeed, new low-latency requirements cannot be satisfied relying only upon extreme virtualization hardware functions. Moreover, conventional with fixed characteristics and functionalities are not appropriate modern electromagnetic environments, which undergo continuous fast variations. Embedded smartness a required feature for widening range possible responses support...

We investigate an anomalous scattering phenomenon exhibited by a lossless system based on metasurfaces. Electromagnetic energy is neither reflected nor transmitted but stored within the to be available again at different time. analytically derive proper excitation conditions and verify response of through set full-wave simulations, demonstrating key role metasurface in enabling such zero-scattering condition. The practical feasibility opportunities offered proposed metasurface-based may open...

The experimental evidence of purely reactive loads impedance matching is here provided by exploiting the special scattering response under complex excitations. study starts with a theoretical analysis reflection properties an arbitrary load and identifies proper excitation able to transform into virtual resistive during time signal applied. To minimize reflections between transmission line, must have frequency, leading propagating tailored temporal envelope. aim this work design and, for...

Virtual absorption concept has been recently introduced as a new phenomenon observed in electromagnetics and optics consisting of theoretically unlimited accumulation energy within finite volume material without dissipation. The anomalous behaviour is achieved by engaging the complex zero scattering eigenmodes virtual absorbing system illuminating it with proper frequency ω = r + jω i , whose value strictly determined characteristics. In this paper, we investigate on position zero-pole pairs...

Any lossless transmission line terminated on an arbitrary reactive load suffers from reflections, due to the high impedance mismatch between real characteristic of and imaginary load. Although several techniques have been proposed achieve matching, a resistive lumped component must be always added at end for ensuring power dissipation achieving required zero reflection. Here, we present way perfect matching condition purely loads by exploiting properties complex frequency excitation. By...

The opportunities offered by energy absorbing, storing, and releasing in lossless systems are here exploited exciting the zero-scattering condition of a metasurface-bounded open cavity. We investigate on so-called virtual absorption supported partially cavity, bounded an infinite reflector metasurface. Starting from theoretical analysis, we analytically find that system exhibits set zeros scattering eigenvalues complex frequency plane, which correspond to anomalous response absorption....

The storage of electromagnetic energy is a typical capability closed cavities, whose impenetrable walls do not allow leakage in the form radiation. Recently, interest open or partially-open cavities able to absorb and store carried by an external illuminating field has stimulated research efforts exploration special exhibiting anomalous scattering properties. In this contribution, we investigate properties partially cavity, bounded on one side infinite reflector other metasurface. We show...

In lossless transmission lines terminated on purely reactive loads reflections cannot be avoided, due to the significative impedance mismatch between real characteristic of line and imaginary load. Several techniques have been proposed achieve matching, all them are based introduction a resistive lumped element at end obtain power dissipation required zero reflection. this contribution, we show way perfect matching condition for by exploiting properties complex frequency excitation, i.e....

In this contribution, we propose a quadratic-gradient metasurface dome operating in the near-field region of dual-polarized phased array able enhancing its grating-lobe-free scanning range without affecting other characteristics. The consists an Huygens unit-cells exhibiting extremely low insertion loss and proper phase shift transmission. main characteristic proposed is profile, which minimizes beam divergence broadside direction, whereas linearly increases off-broadside pointing angles. A...

Antenna arrays with large interelement spacing are marginally used in practical applications despite their highly directive main lobe. Their disuse is primarily attributed to the onset of grating lobes even for low scanning angles. In this contribution, we propose design a gradient metasurface dome able reduce lobe amplitude dual-polarized phased array. The consists an array Huygens unit-cells exhibiting extremely insertion loss and properly designed phase transmission coefficient. proposed...

In this contribution, we present the latest developments from our group on metasurfaces for antenna applications. particular, properties and a possible implementation of non-linear time-varying metasurfaces: first one have been used conceiving powerdependent waveform-dependent mantle cloaks antennas, allowing them to become invisible/visible an electromagnetic wave depending power level or waveform incident wave, respectively; second allows realize Doppler cloaking, which can vanish...

In this contribution, we propose a magnet-less non-reciprocal isolating system based on time-varying metasurfaces. The consists of conventional frequency selective device placed between two metasurfaces, one for up-conversion and down-conversion by the same amount. overall reciprocity is broken exploiting different scattering response from embedded when illuminated opposite directions, since metasurface imparts an conversion directions illumination, but transmitted fields are always as...

In the last two decades, concept of metasurfaces has evolved, leading, nowadays, to unprecedented possibilities. The first generation was based on regular homogeneous periodic structures. This 2D version volumetric metamaterials had a dramatic impact in many application fields, ranging from radio up optical frequencies. Following evolution path metasurface concept, second inhomogeneous structures characterized by quasi-periodical or gradient-like arrangements. spatial modulation properties...

In this contribution, we will present our investigation on design limits of the metasurfaces to be used for enabling virtual absorbing in metasurface-based absorbers. To reach goal, analytically identify conditions under which a properly modulated monochromatic plane wave can virtually absorbed by system, deriving required metasurface values given cavity. The analysis is developed modelling system components, i.e., reactance and cavity input impedance, through an equivalent transmission line...

In this contribution, we exploit virtual perfect matching to achieve impedance of purely reactive loads in lossless transmission lines, by using complex frequency excitation, i.e. a signal having specific temporal shape. The proposed system is lossless, since the load reactive, energy not dissipated, but stored as long excitation condition satisfied, giving rise an interesting singularity transient regime, also known absorption. Then, accumulated released once applied illumination changes.

In this work, we review our recent research on advanced cloaking metasurfaces used to cover monopole antennas. Cloaking devices based passive have demonstrated a dramatic enhancement of the antenna functionalities, thanks additional degrees freedom available in design. Integrating electronic circuits and enabling time modulation can further lead more making covered antennas ever intelligent. framework, vision is extensively use reconfigurable make cognitive adaptive, sensing capabilities...

Virtual absorption concept has been recently introduced as a new phenomenon observed in electromagnetics and optics consisting of an undefined energy accumulation within finite volume material without dissipation. The anomalous behaviour is achieved by engaging the complex zero scattering eigenmodes virtual absorbing system illuminating it with proper frequency, whose value strictly determined characteristics. In this paper, we investigate on position zero-pole pairs frequency plane function...

Virtual absorption concept has been recently introduced as a new phenomenon observed in electromagnetics and optics consisting of an undefined energy accumulation within finite volume material without dissipation. The anomalous behaviour is achieved by engaging the complex zero scattering eigenmodes virtual absorbing system illuminating it with proper frequency, whose value strictly determined characteristics. In this paper, we investigate on position zero-pole pairs frequency plane function...

The aim of this contribution is to review some recent applications metasurfaces and cast them in the scenario next-generation wireless systems. In particular, we show their potentialities overcoming detrimental effects presented by environment communications, discuss crucial role towards practical implementation a smart electromagnetic environment.

In this contribution, we present and discuss the concepts of virtual perfect matching reactive loaded circuits absorption in metasurface-bounded cavities. The anomalous scattering behaviours two cases are here analysed through a corresponding transmission line models, showing how it is possible to enable both phenomenon realistic scenarios deriving operative limits for given load or surface impedance metasurface bounding cavity, respectively. presented study aims highlight connections...