Single-Mode Dual-Band Patch Antenna Based on the Lorentz Model of Dispersive Metamaterials

Based on the Lorentz model of dispersive metamaterials (Lorentz-dispersive metamaterials, in short), a method of generating single-mode dual-band operation of microwave patch antennas is presented. This method is inspired by the unique properties of Lorentz-dispersive materials, which exhibit a higher refractive index at lower frequencies and a lower refractive index at higher frequencies (relative to the material’s resonant frequency). Based on the relation between these refractive indices and wavelengths of antennas, a patch antenna with a Lorentz-dispersive material substrate simultaneously operates at two distinct frequencies with a single electrical size. This phenomenon offers the possibility of generating single-mode radiation over two frequency bands for antenna designs. After studying the properties of the Lorentz-dispersive materials, a split-ring resonator (SRR) is simplified and miniaturized to realize a Lorentz-dispersive metamaterial. A single-mode dual-band patch antenna and its array with
$1 \times 4$
elements are designed to verify the proposed method in sub-6-GHz bands. A rectangular patch antenna with the designed dispersive metamaterial realizes operation at two separate frequencies of 2.6 and 4.1 GHz simultaneously with the dominant
${\rm {TM}_{10}}$
mode. The antenna achieves nearly identical broadside radiation patterns over both frequency bands and gains of 6.9 and 8.1 dBi, respectively.