Notched Circular Microstrip Patch Antenna integrated with a single diode rectifier for energy-harvesting prosthetic leg

In this paper, we describe an RF energy-harvesting circuit printed on a single FR4 substrate to ensure compact and low profile design at 2.1 GHz. The circuit integrates a notched Circular Microstrip Patch Antenna (CMPA) with a fully matched single diode rectifier to form an efficient rectifying antenna. By cutting two electrically small triangular notches, at 45° and 315° of the patch, it is possible to cut-out the 2nd and 3rd harmonics generated by the single diode rectifier, thereby eliminating the need to use the complicated and lossy 0.5 dB ripple Chebyshev low pass filter at the input of the rectifier. In this way, we achieved 2.7V _DC=OUT by measurement, a value which is 4 times larger than conventional 0.65V _DC=OUT at ≤ 0dBm RF incidence. The proposed rectenna circuit is worn as fabric on a prosthetic leg to provide power for the patient´s batteryless health monitoring sensor radio.