Enhancing RF energy harvesting in smart cities with two port MIMO-UWB antenna design using machine learning algorithms

Abstract

This work presents the two port ultra-wide band MIMO antenna with novel isolation structure and dual band RF Rectifier for 3.3 GHz and 4.65 GHz frequencies for RF energy harvesting applications. The anticipated antenna is systematically examined within the ultra-wideband (UWB) range from 3.1 GHz to 10.6 GHz design frequency with four different steps: Antenna 1, Antenna 2, Antenna 3 and Antenna 4 (optimal design) are chosen for comprehensive study. A unique isolation structure was developed between two identical elements separated by 10 mm, resulting in an enhanced isolation of −23.5 dB at 3.15 GHz, −27 dB at 5.8 GHz, −28 dB at 9.26 GHz and greater than −34 dB at 7.5 GHz. The suggested antenna resonates at UWB band and have fractional bandwidth of 118.66 % and a peak gain of 4.1 dB at 3.15 GHz, 3.68 dB at 5.8 GHz, 6.4 dB at 7.5 GHz and 3.2 dB at 9.26 GHz has been obtained. Radiation efficiencies of 92.5 %, 95 %, 90 % and 84.5 % at 3.15 GHz, 5.8 GHz, 7.5 GHz and 9.26 GHz were obtained respectively. The recommended MIMO performance is simulated using HFSS in terms of ECC, DG, MEG and CCL. The results adhere to specified requirements and confirmed by experimentation. An HFSS simulated dataset of reflection coefficient is used as input for the various ML algorithms namely, Support Vector Machine (SVM), Ensemble, k-nearest neighbors’ algorithm (KNN) and Gaussian Process Regression (GPR) models are trained with 80 % of the data and testing with 20 % of the data. The test results are compared and corresponding performance values of MAE, RMSE, MSE & R 2 are 0.00029, 0.00197, 3.87e−6 and 1.0 validation results and corresponding test results are 0.00031, 0.00229, 5.20e−6 and 0.999. Finally, the proposed dual band rectifier with a shorted stub is tested for harvesting applications at 3.3 GHz and 4.65 GHz frequency and it attained RF to DC conversion efficiencies of 69 % and 55.40 % respectively.