Design of Miniaturized Metamaterial Patch Antennas With $\mu$-Negative Loading

Abstract

Recent theoretical studies have shown that circular patch antennas loaded by an inhomogeneous substrate partially filled with a -negative (MNG) metamaterial may in principle support a resonant radiating mode, even if the total size of the radiator is significantly smaller than the wavelength of operation. In those theoretical analyses, MNG metamaterials have been assumed as continuous, isotropic and readily available materials, characterized by a proper dispersion in frequency and by inherent ohmic losses. The fabrication of such compact antennas, however, would require the major effort of designing proper subwavelength inclusions that realize the MNG behavior of the substrate, and consequently a careful design of their geometry, location and orientation. The fabrication of a fully isotropic MNG sample to reside underneath the sub-wavelength patch, moreover, may be challenging with the current technological limitations. In this paper, we first show that the proposed sub-wavelength radiator may operate even when the fabricated MNG sample is not isotropic, due to the specific polarization of the magnetic field in the MNG region. Then, we propose a complete design of the magnetic inclusions, presenting full-wave numerical simulations of the structure, which effectively supports the expected resonant mode, despite the small size of the antenna. The comparisons among analytical results of the patch loaded by: (a) the ideal MNG sample applying a simple cavity model; (b) full-wave numerical simulations of the same antenna considering the presence of the feed; and (c) full-wave numerical simulations of the antenna loaded by the proposed magnetic inclusions, show how our design effectively simulate the presence of an MNG sample, allowing the realistic design of a sub-wavelength metamaterial patch antenna with satisfactory matching and radiating features. This may open up new venues in the realization of efficient metamaterial radiating components for practical purposes.Index Terms-Integrated antennas, magnetic inclusions, metamaterials.

`A Novel Design Algorithm' and Practical Realization of Rectangular Patch Antenna Loaded With SNG Metamaterial

“…So, without using dispersive lossy model (i.e., Lorentz model), the simulated theoretical results cannot give proper realistic results. Here we have used Lorentz model [5,8,9] for MNG:…”

“…After this work, different methods have been proposed to design materials with negative permeability. Split Ring Resonator (SRR), Spiral Resonator (SR), Multiple Split Ring Resonator (MSRR), Complementary Split Ring Resonator (CSRR) and Labyrinth Resonator (LR) are some well known inclusion methods [5,12,13]. For the implementation of MNG loading practically, both radiation and S-parameter performance issues should be meticulously handled so that there remains minimum anomaly between theoretical and practical realization of antenna performance.…”

“…But when inclusions are placed in the partially loaded region, anisotropic MNG region appears for the introduction of SR inclusions in the radiator. Nevertheless, it is enough to guarantee a correct operation of the antenna [5]. Considering these facts, Bilotti et al [5] showed a circular patch antenna with µ-negative loading by using inclusion of SRs.…”

“…Nevertheless, it is enough to guarantee a correct operation of the antenna [5]. Considering these facts, Bilotti et al [5] showed a circular patch antenna with µ-negative loading by using inclusion of SRs. To promote same field distribution inside the antenna, incident magnetic field direction must align with the orientation of the magnetic field of inductive loops so as to provide changing effective permeability to the medium in that direction [5].…”

“…Probably, metamaterial based antennas can be the best solution for all these demands stated above. In [4] and [5] possibility of subwavelength patch using only circular patch has been demonstrated. But yet solution of reduced size rectangular patch antenna has not been reported in literature.…”