Compact Circularly Polarized Microstrip Antenna with Harmonic Suppression for Enhanced Ambient RF Energy Harvesting

This work presents the design of a compact circularly polarized antenna with harmonic suppression for potential application in RF energy harvesting. The designed antenna operates at 2.4 GHz for suitable harvesting of energy from Bluetooth, Wi-Fi and other devices operating in the ISM band. The radiating unit comprises a rectangular patch embedded with cross shaped slot for harmonic suppression. Four unique bulb shaped structures with suitable modifications are also introduced close to the diagonal edges of the radiator to realize circular polarization. The designed antenna achieves a - 10 dB operating bandwidth of 80 MHz and axial ratio bandwidth of 20 MHz at the resonating frequency of 2.40 GHz. An overall gain of 3.9 dBi is also noticed within a compact circuit dimension of 47.2 × 53.7 mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>.