A Compact Dual-Band Monopole Antenna Loaded with CRLH Unit Cell Exploiting Meandered Line Geometry

This paper presents a novel, compact composite right/left handed transmission line based monopole antenna loaded with meander line structure. The proposed antenna is printed on 25 × 25 × 1.6 mm
³
FR4 substrate having dielectric constant of 4.4 + j0.088. To give an insight into working mechanism of the antenna parametric study, electric field distribution and equivalent circuit model have been explained in detail. It is found that the loading of CRLH transmission line leads to miniaturization of the antenna design and miniaturized electrical size of the antenna is calculated as 0.26 λ × 0.26 λ × 0.016 λ, where λ is free-space wavelength corresponding to lowest resonant mode i.e. 3.13 GHz. Measured results show that the suggested antenna exhibits dual-band resonance at 3.09–3.27 GHz (centered at 3.17 GHz) and 4.40–4.50 GHz (centered at 4.47 GHz). A good impedance matching is obtained at both operating bands. It provides simulated peak gain of 1.93 dB and 2.66 dB with corresponding radiation efficiencies of 88.83 % and 78.87 % at 3.13 GHz and 4.49 GHz, respectively. The dipole pattern is obtained in azimuthal plane (H-plane) and omnidirectional pattern is obtained in elevation plane (E-plane). In addition, the presented antenna offers excellent co-to-cross polarization ratio at both the bands.