Numerical homogenization and synthesis of wave polarizers through the Material-by-Design paradigm
A Material-by-Design (MbD) strategy is introduced for the design of multi-layer wave polarizers based on metasurfaces with arbitrarily-shaped unit cells. Following the MbD paradigm, the design is carried by integrating a solution-space exploration block, an electromagnetic simulation block (exploiting a full-wave Method-of-Moments with periodic boundary conditions), a homogenization block, and a cost function evaluation block. Numerical example showing the effectiveness of the proposed strategy is presented.
A frequency-tunable metamaterial-based antenna using a reconfigurable AMC groundplane
The design of a low-profile narrowband antenna that is tunable over a wide frequency range is presented. A spline-based Ultra-Wideband (UWB) antenna is synthesized by means of a time-domain-based PSO and is mounted on top of a reconfigurable Artificial Magnetic Conductor (AMC) obtained by replicating a square unit cell in a 15×15 periodic lattice. The AMC is composed by a planar array of periodic metallic strips printed on top of a PEC-backed dielectric substrate, connected by tunable capacitors (varactors), and has been designed to work within the 1-4 [GHz] bandwidth. The reflection coefficient of the resulting narrowband antenna system can be easily controlled inside a wide frequency range by tuning the capacitance value C of the varactors inside the AMC groundplane.
Best approximation and moduli of smoothness: Computation and equivalence theorems
In this paper we investigate the trigonometric series with the @b-general monotone coefficients. First, we study the uniform convergence criterion. The estimates of best approximations and moduli of smoothness of the series in uniform metrics are obtained in terms of coefficients. These results imply several important relations between moduli of smoothness of different orders (in particular, Marchaud-type inequality) and best approximations.