Abstract
A multiband coplanar waveguide (CPW)-fed antenna loaded with metamaterial unit cell for GSM900, WLAN, LTE-A, and 5G Wi-Fi applications is presented in this paper. The proposed metamaterial structure is a combination of various symmetric split-ring resonators (SSRR) and its characteristics were investigated for two major axes directions at (x and y-axis) wave propagation through the material. For x-axis wave propagation, it indicates a wide range of negative refractive index in the frequency span of 2–8.5 GHz. For y-axis wave propagation, it shows more than 2 GHz bandwidth of near-zero refractive index (NZRI) property. Two categories of the proposed metamaterial plane were applied to enhance the bandwidth and gain. The measured reflection coefficient (S11) demonstrated significant bandwidths increase at the upper bands by 4.92–6.49 GHz and 3.251–4.324 GHz, considered as a rise of 71.4% and 168%, respectively, against the proposed antenna without using metamaterial. Besides being high bandwidth achieving, the proposed antenna radiates bi-directionally with 95% as the maximum radiation efficiency. Moreover, the maximum measured gain reaches 6.74 dBi by a 92.57% improvement compared with the antenna without using metamaterial. The simulation and measurement results of the proposed antenna show good agreement.
Highlights
The development of metamaterial has received significant interest as a material for the creation of numerous novel structures with unconventional electromagnetic properties and Sensors 2020, 20, 457; doi:10.3390/s20020457 www.mdpi.com/journal/sensorsSensors 2020, 20, 457 noticeably enhanced performances [1,2]
We propose a multiband coplanar waveguide (CPW)-fed antenna array covered with a planar investigated metamaterial (MTM) superstrate based on a near-zero refractive index (NZRI) and double-negative metamaterials (DNG) over a wide frequency range
The negative electric permittivity and permeability are usually used as the material parameters that describe how materials polarize in the presence of electric and magnetic fields, which leads to achieving a negative refractive index
Summary
The development of metamaterial has received significant interest as a material for the creation of numerous novel structures with unconventional electromagnetic properties and Sensors 2020, 20, 457; doi:10.3390/s20020457 www.mdpi.com/journal/sensors. The DNG supports an electromagnetic wave where the phase and group velocities propagate in opposite directions This allows new electromagnetic properties [7,8] and applications in antenna design, biomedical, and wireless technologies [9]. Antenna performance has been significantly improved using metamaterial, which offers improved size miniaturization, gain, bandwidth, as well as decreased cost [14,15,16]. SRR unit cell structures have been investigated for antenna design miniaturization, creating multiband operation, and improving bandwidth and gain [23,24]. We propose a multiband CPW-fed antenna array covered with a planar investigated metamaterial (MTM) superstrate based on a near-zero refractive index (NZRI) and double-negative metamaterials (DNG) over a wide frequency range. It can be seen that the proposed antenna offers significantly increased bandwidth and gain over similar antennas
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