In this work, a Complementary Folded Triangle Split Ring Resonator (CFTSRR) loaded triband mobile handset planar antenna is presented. The proposed antenna consists of a dumbbell-shaped radiating element and two CFTSRR metamaterial unit cells. The dumbbell-shaped radiating element resonates at 5 GHz. The presence of CFTSRRs additionally offers two lower band resonance. The CFTSRR-1 and CFTSRR-2 exhibit negative permittivity at 1.8 GHz and 2.4 GHz, respectively. The proposed antenna is designed to resonate at 1.8 GHz (GSM1800 MHz), 2.4 GHz, and 5 GHz (IEEE802.11ax) for voice and Wi-Fi applications of the mobile handset, respectively. The proposed antenna demonstrates compactness up to 88.6% at 1.8 GHz. The parametric studies are investigated to optimize the antenna in desired frequency bands by using Ansys HFSS19 software. The simulated and measured results are discussed. The measured result shows -10 dB reflection coefficient with bandwidth about 250 MHz (1.6 GHz-1.85 GHz), 50 MHz (2.375 GHz-2.425 GHz), and 225 MHz (4.925 GHz-5.15 GHz) which are 14.5%, 2%, and 5% respectively around their center frequencies. The measured maximum gain is approximately 1.7 dBi, 8 dBi, and 11.5 dBi for 1.8 GHz, 2.4 GHz, and 5 GHz, respectively.
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