A Compact Resistively Loaded Metamaterial Absorber for 2.4 GHz RF Energy Harvesting With Impedance‐Matched Rectifier Analysis

Abstract

This work presents a compact resistively loaded square‐diamond resonator metamaterial absorber for RF energy harvesting at 2.4 GHz. The unit cell has an electrical size of 0.16 λ × 0.16 λ × 0.013 λ and incorporates symmetrically positioned lumped resistive loads to support RF power extraction. Full‐wave CST simulation shows 99.92% absorption at resonance, with the retrieved surface impedance indicating close matching to free‐space impedance. The symmetric square‐diamond geometry provides a polarization‐insensitive response under normal incidence and maintains stable simulated absorption for both TE‐ and TM‐polarized oblique excitation up to 60°. Surface‐current, electric‐field, impedance, and equivalent‐circuit analyses indicate that the absorption behavior is primarily determined by the induced current distribution, field localization, and controlled dissipation through the resistive loads. The simulated RF power‐transfer efficiency to the resistive loads reaches 96.74% at 2.4 GHz. The impedance‐matched two‐diode rectifier provides 75.7% AC‐to‐DC conversion efficiency at RL = 2.36 kΩ, resulting in a simulated cascaded RF‐to‐DC efficiency of 73.23% at 5 dBm input power. A fabricated 4 × 2 absorber array is experimentally characterized, and the measured absorption peak remains close to the simulated resonance. Within this validation scope, the proposed RL‐SDR‐MMA provides a compact RF capture surface for 2.4 GHz energy harvesting, supported by simulated rectifier‐stage conversion analysis.