Las bobinas de Helmholtz habitualmente se usan para establecer una zona de campo magnético conocido y uniforme para diversas aplicaciones. Es importante conocer la zona donde dicho campo magnético es uniforme con las distintas variables espaciales x, y, z. En la zona donde se genera un campo magnético uniforme, se pueden hacer las calibraciones de sensores magnéticos y sondas de campo magnético, en un rango de bajas frecuencias. Este trabajo se dedica a calcular y medir el campo magnético generado por las bobinas de Helmholtz y determinar la uniformidad y la exactitud del campo magnético respecto al centro de simetrı́a del sistema estudiado.
Abstract-This paper presents the study of an artificial material, made up of a periodic structure, defined by a unit cell, consisting of a finite number N of periodic layers of thin conducting cylinders placed between two dielectric planes. These artificial materials known as metamaterials can be regarded as a homogeneous material with effective constitutive parameters impossible to achieve with naturally occurring materials, such as negative values for both magnetic permeability and electric permittivity. An analytical model has been developed to study the effective electric permittivity of the whole system in terms of the unit cell dimensions and the frequency of the incident electromagnetic wave. Simulations of the effective electric permittivity of the metamaterial were performed by varying the geometry of the metamaterial. This analysis enables the design and construction of structures with properties that make them an attractive candidate for shielding applications in the range of microwave frequencies. The metamaterial has been constructed with four rows of 5 bronze conducting rods each. We have made experimental measurements of the shielding effectiveness of these materials when subjected to a electromagnetic plane wave with electric field polarized along the direction of the conducting rods, and conversely, with electric field polarized perpendicular to the rods. Non-zero values for shielding effectiveness were observed in the first polarization, and zero values in the second case.
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