RF energy harvester in the proximity of an aircraft radar altimeter

This paper presents the design and characterization of a rectenna-based energy harvester for low-power aircraft sensors. The harvester is placed on the aircraft skin in the proximity of the radar altimeter transmit antenna with power densities between 0.04 μW/cm
²
to 2.2 μW/cm
²
around 4.3 GHz. Several diodes were investigated via source-pull, and the chosen devices integrated with a patch antenna to directly charge a capacitor which serves as the energy storage device. The harvester is able to collect -23.2dBm of power from an incident power density of 0.65 μW/cm
²
, and the time it takes the harvester to reach 63% of its open-circuited voltage is characterized for several designs.