Can anyone help me out in understanding the nonlinear models for RF energy harvesting. Specifically, I would like to know the impact of multiple antennas on the amount of harvested energy. How much can be gained by utilizing multiple antennas.
I need theoretical understanding as well as mathematical nonlinear model for RF energy harvesting.
Thanks
In order to harvest Rf energy or power some sort of rectifier is required..in the most simple case..a diode..with linear elements one can only play on Rf heating which would be rather inefficient in particular for low power densities..
If you use several antennas you can either combine them before or after the rectifier. If you combine them before the rectifier, then they will act as one, larger, antenna, with a particular beamshape. If you rectify the signal of each and then combine the rectified signals you get the sum of the power of each of the antennas. If they are small antennas then each will receive a small signal and the rectifier efficiency will be small. If you use a large antenna with a narrow beam it can harvest a lot of power and overcome the rectifier inefficiency, but only from a narrow range of directions. If you use several so their beams overlap a bit , with their own rectifiers, and combine them after the rectifiers, you can harvest from all directions with good efficiency.
The most used components to harvest RF power are diodes (Schottky for example) and transistors (JFET, ...). The key to having the maximum power at the output is to have an adequate matching network in the desired frequency band, and also to properly characterize the used component for energy harvesting (Diode or transistor). Good luck.
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