Metamaterials can be defined as a joint of small artificial cells or elements which could be small scatterers or apertures which are distributed in a regular array throughout a region of space, in order to obtain some desirable macroscopic electromagnetic behavior which would be difficult to obtain with natural materials. In the beginning, metamaterials were first an interesting theoretical concept, then they were some periodic dielectric-conductor structures with unusual measured properties, and finally they became an important part of some modern electronic devices. Due to the fast development in the area and considering the fact that it is not common to find reviews of the metamaterial theory written in Spanish language, this work is an updated state-of-the-art related to metamaterials properties, classification and applications, based on the most relevant research works in the area. As a result from this review, an updated metamaterial classification is given as a contribution. Main metamaterial properties, design techniques and applications are shown. Moreover, a perspective of the metamaterial future is presented, in order to generate interest in this area of research.

Characterization of a physical system is an important issue to approach some applied physics and engineering problems. The complex natural resonance frequencies of the system which are included in its impulsive response are characteristic of such system and are part of its description. Few works written in English language show a comparison among discrete methods that extract natural complex frequencies from a system impulsive response. Much less common is to find works written in Spanish language about this important research topic. Given this situation, important discrete numeric methods to estimate the complex natural resonance frequencies of a system through its impulsive response are described, tested and compared in different simulation scenarios in this document. According to the obtained results, the matrix pencil method with a SVD filter is the less sensitive method to the noise, while the Prony method and its different versions are the fastest ones. Scenarios that could be more suitable for each method are discussed.

The estimation of complex natural frequencies in linear systems through their transient response analysis is a common practice in engineering and applied physics. In this context, the conventional Generalized Pencil of Function (GPOF) method that employs a matrix pencil of degree one, utilizing singular value decomposition (SVD) filtering, has emerged as a prominent strategy to carry out a complex natural frequency estimation. However, some modern engineering applications increasingly demand higher accuracy estimation. In this context, some intrinsic properties of Hankel matrices and exponential functions are utilized in this paper in order to develop a modified GPOF method which employs a matrix pencil of degree greater than one. Under conditions of low noise in the transient response, our method significantly enhances accuracy compared to the conventional GPOF approach. This improvement is especially valuable for applications involving closely spaced complex natural frequencies, where a precise estimation is crucial.

The estimation of complex natural frequencies in linear systems through its transient response analysis is a common practice in engineering and applied physics. In this context, the conventional Generalized Pencil of Function (GPOF) method that employs a matrix pencil of degree one, utilizing Singular Value Decomposition (SVD) filtering, has emerged as a prominent strategy to carry out a complex natural frequencies estimation. However, some modern engineering applications increasingly demand higher accuracy estimation. In this context, some intrinsic properties of Hankel matrices and exponential functions are utilized in this paper in order to develop a modified GPOF method which employs a matrix pencil of degree greater than one. Under conditions of low noise in the transient response, our method significantly enhances accuracy compared to the conventional GPOF approach. This improvement is especially valuable for applications involving closely spaced complex natural frequencies, where a precise estimation is crucial.

Several microwave power transfer efficiency applications involve interfaces where more than half of the incident wave's power density is frequently reflected. To enhance this efficiency, various media for impedance matching between volumetric materials used in biomedical, industrial, and environmental remediation applications have been proposed. However, they either exhibit high losses or require a specialized manufacturing process. Given that the use of volumetric metamaterials as matching media is an underexplored area of research, the authors of this paper first propose, model, and simulate a metallic cubic conductor metamaterial to investigate its understudied parameters. Then, the metamaterial is simulated in a quarter-wavelenght impedance transformer configuration to improve the efficiency of electromagnetic wave power transfer at an air-water interface. Numerical simulations and analytical modeling of this configuration show that the power density of the transmitted wave more than doubles respect to the interface without the proposed matching system. This improvement is achieved since the metamaterial has an intrinsic impedance within the same range as that of the materials to be matched, since the metamaterial is a low loss, a positively polarizable and exhibits a mu-near zero behaviour. In contrast to other impedance matching media, the suggested metamaterial has a low attenuation constant, offers a wide range of intrinsic impedance values, and can be constructed with readily available materials.