1,721,102 research outputs found
Caratterizzazione di antenne su substrati non tradizionali ed analisi frattale, in collaborazione con il Prof. Nader Engheta dell'Università di Philadelphia, USA
No full text
Power-transmission enhancement through a sub-wavelength hole in a perfect conductor by employing metamaterials
No full textSubwavelength Planar Leaky-Wave Components with Metamaterial Bilayers
No full textThe potential use of metamaterial planar bilayers for synthesizing compact subwavelength leaky-wave radiators in the microwave regime is analyzed in detail. In particular, the possibility of pairing "complementary" metamaterials in order to reduce the dimensions of microwave components is explored for the leaky-wave operation of an open waveguide consisting of a grounded pair of planar layers. In connection with our similar findings in other setups employing such complementary pairings, here we show how the compact resonance at the interface between "negative" and "positive" materials may also be properly exploited in this context. Choosing materials with low constitutive parameters, moreover, shows to be effective for enhancing the directivity of these components. We explore in detail the notable guidance and radiation properties of the anomalous natural modes supported by these bilayered structures, giving some physical insights into the anomalous phenomenon and considering the possible limitations in some realistic setup
Miniaturized Circular Patch Antenna with Metamaterial Loading
No full textIn this contribution, we present a possible implementation of a miniaturized circular patch antenna with metamaterial loading. In previous theoretical investigations we have already shown that it is possible to excite a resonant radiating mode in a circular patch by using an inhomogeneous substrate made of the combination of a regular dielectric and a metamaterial exhibiting a negative real part of the permeability. While in our previous works we have considered the metamaterial as an ideal isotropic material described by a Lorentz-like dispersion, here we propose a possible implementation of the same structure, employing proper resonant inclusions. A theoretical cavity-model analysis allows determining qualitatively the expected near field distribution of the antenna at its resonance and therefore optimizing the location and orientation of the inclusions. The final layout has been simulated through a full-wave commercial code and the resulting matching and radiation features, in good agreement with our previous theoretical investigations, demonstrate the possibility of realizing a resonant sub-wavelength patch exhibiting good matching and radiating feature
Metamaterial grounded planar bilayers supporting leaky waves: principles and applications
No full text
Power-Transmission Enhancement Through a Sub-wavelength Hole in a Perfect Conductor by Employing Metamaterials
No full textSubwavelength, compact, resonant patch antennas loaded with metamaterials
No full textWe analyze the matching and radiation properties of subwavelength resonant patch antennas filled with double-negative, double-positive, and/or single-negative metamaterial blocks. Analyzing the theoretical limits inherently present when loading such common radiators with metamaterials, we show how these configurations may exhibit in principle an arbitrarily low resonant frequency for a fixed dimension, but they may not necessarily radiate efficiently when their size is electrically small. However, interesting possibilities are suggested to overcome these limitations by employing circular or more complex patch geometries in order to select specific modes that, when appropriate loading ratios between the filling materials are chosen, also ensure radiation performance comparable qualitatively with a regular patch radiator of standard dimensions. Realistic numerical simulations, considering material dispersion, losses and the presence of the antenna feed are presented, showing how a practical realization is foreseeable. This may open novel venues in the design of small-scaled radiators with enhanced performance, which is of interest for many applications
- …
