Design of a 2.45 GHz rectenna for electromagnetic (EM) energy scavenging

A compact dual polarized rectenna operating at 2.45 GHz is presented. It consists of a square aperture coupled patch antenna with a cross shaped slot etched on its surface that permits a patch side reduction of 32.5%. The patch size is 3.4 cm by 3.4 cm. The antenna is dual linearly polarized with each orthogonal polarization received by an appropriately placed coupling slot. The received signal from each slot output is rectified by a voltage doubling circuit and the doubler DC output signals are combined allowing the rectenna receive signals of arbitrary polarization. The circuit is optimized for low input power densities using harmonic balance. Simulated rectifier maximum RF-to-DC conversion efficiency values of 15.7% and 42.1% were obtained for input available power levels of -20 dBm and -10 dBm respectively at 2.45 GHz. The measured results are in agreement with the simulation.