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480 results on '"Vegni, L"'

1. Optical cloaking with metamaterials

Author

Bilotti, F., Tricarico, S., and Vegni, L.

Subjects
Physics - Optics, Physics - General Physics
Abstract

In this contribution, we present the design of cylindrical electromagnetic cloaks working at optical frequencies, making use of layered structures of plasmonic and non-plasmonic materials. The simulated results confirm the validity of the proposed approach and show a rather broad-band behavior of the cloaking device., Comment: 2 pages, 2 figures, submitted to EOS Topical Meeting on Nanophotonics, Photonic Crystals and Metamaterials - TOM 3 - 2008

Published
2008

4. Exponentially tapered non uniform transmission lines

Author

Vegni, L., Urbani, F., and Toscano, A.

Subjects
Microwave transmission lines -- Research, Semiconductors -- Research, Business, Electronics, Electronics and electrical industries
Abstract

In this paper we solve the transmission line equations for a Non Uniform Transmission Line (NUTL). The analytical method used is different to the Kuroda's one. First we find the solution in terms of voltage and current waves, then the expression of input impedance that allow us to find the R=const and X=const loci. In particular the solution is found for an exponential NUTL. We find the correspondent representation of the Smith Chart. The NUTL has more advantages with respect to the uniform one. In fact we can use the Generalised Smith Chart to solve easily the problem of a NUTL loaded by a complex impedance. Moreover, we can use the NUTL to match lines with different sections and to model multilayered semiconductor structures. Finally, we show the normalised power behaviour for an exponentially tapered NUTL when the tapering factor is varying.

Published
1997

5. Spectral electromagnetic modeling of a planar integrated structure with a general grounded anisotropic slab

Author

Toscano, A. and Vegni, L.

Subjects
Electromagnetic fields -- Research, Anisotropy -- Research, Business, Computers, Electronics, Electronics and electrical industries
Abstract

In this paper a formulation for the solution of the electromagnetic field in vertically stratified structures with a general anisotropic grounded slab under planar electric excitation conditions is presented. The development of the solution is obtained by using the two-dimensional (Fourier) transform applied to the partial differential equations describing the electromagnetic field, which can be expressed in terms of dyadic electric Green functions. Moreover, a spectral equivalent circuit representation of the solution, separated into its spectral transverse electric (TE) and transverse magnetic (TM) components (with respect to the vertical direction), is given. It is demonstrated that such a spectral circuit representation is always possible when the constitutive (Mathematical Expression Omitted) and (Mathematical Expression Omitted) tensors are reduced to their diagonal form. Finally, we present the transmission-line representation for an unbounded gyrotropic medium with vertical preferred axis, and we then apply this theory to a planar structure with an anisotropic biaxial grounded slab and an electric horizontal point source embedded in it. Numerical examples of evaluation of the radiated pattern and noteworthy information about the radiation on the horizon plane are given with constraints on the electromagnetic parameters, thickness of the slab, working frequency, and source position.

Published
1993

6. From artificial engineered materials to metamaterials: 10th anniversary of the Rome workshops on 'Metamaterials and Special Materials for Electromagnetic Applications and TLC'

Author

BILOTTI, FILIBERTO, Pelosi G, TOSCANO, ALESSANDRO, Vegni L., Bilotti, Filiberto, Pelosi, G, Toscano, Alessandro, and Vegni, L.

Subjects
Metamaterials
Abstract

Metamaterials Congress was initiated in 2007 by the FP6 Network of Excellence Metamorphose as the fusion between the series of conferences Bianisotropics and the series of the international workshops Metamaterials and Special Materials for Electromagnetic Applications and TLC. This year we celebrate the 20th anniversary of the Bianisotropics (previously called Bi-isotropics) conference and the 10th anniversary of the meta-workshops. In this contribution, we present a brief history of the meta-workshops and how they merged with Bianisotropics to originate the Metamaterials Congress. In particular, by using the paradigmatic example of the artificial chiral materials, we would also like to reflect the status of the research on complex media in the late 90s and in the beginning of the new century, in order to highlight the reasons behind the contemporary origin of the meta-workshops and of the network Metamorphose.

Published
2013

42. Electromagnetic modelling and numerical simulation of patch antennas with metamaterial loading

Author

Vegni L, BILOTTI, FILIBERTO, Vegni, L, and Bilotti, Filiberto

Abstract

In this paper, we review the electromagnetic modelling, the numerical simulation and the design of patch antennas loaded with metamaterials. The employment of these artificially engineered artificial metamaterials allows to obtain miniaturized (i.e. truly sub-wavelength) radiators. Interestingly, the proposed antennas, even if electrically small, work as resonating radiators and, thus, can be easily matched. The remaining performances of these antennas (directivity, radiation efficiency, gain) are also very promising, especially if compared with conventional small antennas. These promising results are now under the experimental verification in a collaborative international project within the European Network of Excellence METAMORPHOSE.

Published
2008

50. Varchi elettronici per l’anagrafe animale: influenza dell’angolazione del bolo

Author

BILOTTI, FILIBERTO, Di Rosa P, Guattari G, SAPIA, Carmine, TOSCANO, ALESSANDRO, Vegni L., Bilotti, F, Di Rosa, P, Guattari, G, Sapia, Carmine, Toscano, A, Vegni, L., Bilotti, F., DI ROSA, P., Guattari, Giorgio, Toscano, A., F., Bilotti, DI ROSA, Pietro, G., Guattari, A., Toscano, L., Vegni, Bilotti, Filiberto, and Toscano, Alessandro

Abstract

Un elemento che sensibilmente influenza i parametri di funzionamento del sistema di identificazione a radiofrequenza, è la qualità dell’antenna di lettura, ed in particolare la sua geometria e la sua potenza. Questo perché le caratteristiche proprie dell’antenna di lettura, vanno ad influenzare in maniera non trascurabile il campo di lettura del bolo, e quindi le condizioni di utilizzo senza errori. In questo contributo vengono presentati dei nuovi risultati sperimentali relativi ai valori del campo di lettura del bolo, valutati in funzione della posizione del bolo stesso rispetto all’antenna di lettura, ovvero in funzione dell’angolo di alzata ed in funzione dell’orientamento (angolazione) del bolo rispetto a quello dell’antenna di lettura.

Published
2008

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