High-isolated WiFi-2.4 GHz/LTE MIMO antenna for RF-energy harvesting applications

Abstract

In this article, a two-port novel structure with a common shared ground stub with enhanced isolation for RF-energy harvesting for WiFi-2.4 GHz/LTE applications is presented. The optimized antenna (antenna (4): 0.6λ0 × 0.4λ0 × 0.0128λ0 mm3) is selected as proposed antenna at design frequency (f0 = 2.4 GHz) among antennas (1–4) after study of simulated results through HFSS version 18.2. Two optimized identical elements are closely separated at 0.067 λ0 distance and an enhanced isolation (greater than 49 dB) and perfect impedance matching have been obtained. Proposed antenna covers a wide bandwidth of 2.25–2.98 GHz (simulated), 2.24–3.05 GHz (measured) and fractional bandwidth of 27.91% (simulated), 30.62% (measured) respectively with 2.4 & 2.8 GHz resonance. A peak gain of 2.4 dB at 2.4 GHz and 4.7 dB at 2.8 GHz has been obtained. The antenna exhibits a 95.2% radiation efficiency and 0.8 W/kg specific absorption rate (SAR). MIMO performance metric of the proposed antenna in terms of envelope correlation coefficient (ECC), diversity gain (dB), total active reflection coefficient (TARC), mean effective gain (MEG), and channel capacity loss (CCL) has been evaluated and found in close agreement with practical standards. Moreever, the proposed antenna is further tested for harvested power wherein a maximum harvested voltage of 4.7 V, 4.88 mW Friis equation output, 2.91mW harvested output power and 54.98% power conversion efficiency in 2.4–2.5 GHz band at 20dBm power source are recorded.