The knowledge of the electromagnetic constitutive properties of materials is crucial in many applications. Free-space methods are widely used for this purpose, despite their inherent practical difficulties. This paper describes an affordable free-space experimental setup for the characterization of flat samples in 1–6 GHz in a non-anechoic environment. The extracted properties are obtained from the calibrated Scattering Parameters, using a frequency-by-frequency solution or a multi-frequency reconstruction. For the first, we describe how the Time-Domain Gating can be implemented and used for filtering the signals. For the latter, a weighting factor is introduced to balance the reflection and transmission data, allowing one to have a more favorable configuration. The different role of transmission and reflection measurements on the achievable results is analyzed with regard to experimental uncertainties and different noise scenarios. Results from the two strategies are analyzed and compared. Good agreement between simulation, measurement and literature is obtained. According to the reported results for dielectric materials, there is no need of filtering the data by a Time-Domain Gating in case of the multi-frequency approach. Experimental results for Polymethylmethacrylate (PMMA) and Polytetrafluorethylene (PTFE) samples validate both the setup and the processing.

The element-free Galerkin method (EFG) has specific characteristics that require the usage of techniques and data structures in order to provide efficient calculation. This paper address two problems concerning the EFG implementation. The point location problem, which must find in which subdomain the integration point is located, and the influence domain problem, which must find the nearest nodes to build an influence domain and construct the shape functions. This work proposes the use of new data structures and algorithms in order to solve these problems, speeding up the method and providing a fast and correct influence domain construction

A novel design for a planar artificial magnetic conductor (AMC) with meander line element is used to achieve miniaturization, reduction in the second/first resonant frequency ratio, and multi-band operation. It is known that various parameters—such as geometry, dielectric substrate thickness, the gap between patches, the length and width of a patch, the size of unit cell, permittivity, and permeability—strongly affect the resonant frequency. To obtain a miniaturized AMC, in this paper, we investigate the role of the metallic patch effective length on resonant frequency. Meander-shape is used to change the effective length in the direction of the incident wave polarization. A discussion of the design parameters and the electric field distribution is presented. Six different configurations are proposed. Miniaturization and reduction in the first/second resonant frequency ratio is achieved. In addition, the meander-shape allows the appearance of different operating bands that depend on the number of meanders. For instance, four bands are observed for one meander (U-shape). Therefore, a simple way to obtain AMC miniaturization and multi-band devices is proposed. The results are obtained by the finite element method. To validate our design some results have been compared against experimental testing presented in literature.

A metamaterial lens was designed based on a two-dimensional host transmission line network loaded with inductors and capacitors. The planar negative refractive index (NRI) periodic structure, consisting of a unit cell array with a concave side, works as a curved lens matched to free space operating at S-Band. An equivalent unit cell dispersion relation was developed to determine the transmission characteristics at the operating frequency range. The challenge in the metamaterial lens design is to increase the focal distance. In the simulated system, a high energy level throughout a focal region was observed in the whole frequency range. An equivalent bulky material is used as a resource to reduce computational effort.