Influence of permittivity and substrate thickness for miniaturization of artificial magnetic conductor

摘要

The influence of permittivity and substrate thickness at the resonance frequency of artificial magnetic conductor is investigated. It is known that various parameters such as geometry, dielectric substrate thickness, gap between patches, length and width of patch, size of unit cell, permittivity and permeability strongly affect the resonance frequency. In attempts to elucidate the miniaturization process, as reference, a square patch with a unit cell of size 10 mm × 10 mm has simulated and a resonance frequency of 5.75 GHz has obtained. The device has illuminated by a plane wave with polarization in the y direction. Simulations have been employed to appreciate the behaviour of resonance frequency in function of substrate thickness, and permittivity. The results are supported by finite element method (FEM), using the commercial software COMSOL Multiphysics. Our findings show that there is a decrease at the resonance frequency owing to increase both permittivity and substrate thickness, while an opposite effect has been noted when the gap size between consecutive metals patches is increased. This means that the effect of increasing the dielectric thickness is equivalent to increasing effective permittivity of the system. We believe that the responsible mechanism for this behaviour is the induced electric polarizability on top of metal surface. Therefore, this work suggests that an efficient way to reduce resonance frequency is to look for geometries that maximize net induced electric polarizability and an analysis of electric field distribution could be used in order to design novel structure.