Efficient and Sensitive Electrically Small Rectenna for Ultra-Low Power RF Energy Harvesting

Area of Science:

• Electrical Engineering
• Electromagnetics
• Antenna Theory

Background:

• Electrically small antennas are crucial for miniaturized electronic devices.
• Efficient radio frequency (RF) energy harvesting is essential for batteryless systems.
• Existing rectenna designs often face limitations in efficiency and sensitivity.

Purpose of the Study:

• To design, fabricate, and measure a novel electrically small antenna.
• To develop a highly efficient and sensitive electrically small rectenna.
• To explore the application of rectenna arrays for batteryless wireless sensor node powering.

Main Methods:

• Fabrication and measurement of an electrically small antenna (ka=0.415).
• Integration of the antenna with a single-diode rectifier for rectenna formation (ka=0.53).
• Evaluation of rectenna performance, including efficiency and sensitivity at 868 MHz.
• Investigation of rectenna-array configurations for enhanced DC output.

Main Results:

• The antenna exhibits intrinsic matching to 50 Ω, omni-directional pattern, and 93% simulated efficiency.
• The rectenna achieves 22.5% efficiency for -19 dBm input power and a sensitivity of -44 dBm.
• The rectenna can power a small device with 118 μW at 2.25 μW/cm² input power.
• Rectenna arrays deliver 172 μW at 2.85 V for 0.1237 μW/cm² power density.

Conclusions:

• A highly efficient and sensitive electrically small rectenna has been demonstrated.
• The developed rectenna technology is suitable for powering small electronic devices and enabling batteryless operation.
• Rectenna arrays offer a viable solution for robust RF energy harvesting in wireless sensor networks.