Devices and methods for wireless power harvesting and backscattering communications

A self-adaptive backscattering device, comprising:

• an antenna for receiving and transmitting radio frequency (RF) signals;
• a non-linear element coupled to the antenna;
• and
• a switch for operably coupling the non-linear element to a wireless power harvesting (WPH) load, wherein
• when the switch is on, the non-linear element is connected to the WPH load for harvesting RF signals incident on the antenna to direct current (DC) energy in a WPH mode;
• when the switch is off, the device switches from the WPH mode to a harmonic backscattering (HB) mode for transmitting harmonic backscattered RF signals through the antenna, and
• the switch self-adaptively switches between on and off based on harvested DC energy, wherein
• the switch is turned off when the harvested DC energy in the WPH mode increases to a first level;
• and
• the switch is turned on when the harvested DC energy decreases to a second level,
• wherein the first level corresponds to a logic high bias of the switch;
• and the second level corresponds to a logic low bias of the switch.