Modern electronic devices often include one or more phases of stand-by, where they waiting for a wakeup order from a distant actuator (remote control). These devices tend to be increasingly present in homes and in commercial buildings, especially in the field of building automation systems. Stand-by periods are characterized by consumption levels well below those in active mode, but stand-by periods are generally large compared to active periods. This fact, combined with the proliferation of devices, leads to annual consumption which may exceed 10% of the annual household electricity bill. This study proposes a new approach to waking up of stand-by devices. Instead of continuous monitoring of the arrival of the wake-up signal, the receiver is completely asleep and woke up through a pulse of energy transmitted via electromagnetic waves. Once the data receiver module is activated, information is sent to validate the wake-up order. In view of the expected ranges for the system and normative constraints related to exposures to electromagnetic fields, only a small amount of energy is available at receiver level for performing the wake-up. Several RF-DC rectification circuit (rectenna) topologies in microstrip technology are studied through circuit and electromagnetic simulation. The chosen topology has been optimized to provide a good level of DC voltage at low levels of incident RF power. A matching impedance other than 50 W between the converter and the receiving antenna was used. All these results have been validated experimentally. For the data receiver circuit, several operating scenarios were compared. The demodulation stage uses the rectenna as a diode detector to minimize consumption and complexity of implementation. The overall system has been tested and substantial gains are obtained for several types of devices, in terms of annual consumption, compared to classical stand-by devices. At the same time, a reconfigurable electromagnetic energy receiver architecture is proposed. It offers the advantage of exploiting a wide range of incident power, which is not the case of conventional rectenna structures. Rectennas fabricated in discrete and integrated technology are used, connected to a common antenna through an integrated antenna switch. The proposed system is self-adaptive and the test results show significant improvements in the amount of energy collected compared to individual rectennas. Finally, the phenomenon of voltage reversal in unbalanced rectenna associations is highlighted and possible solutions are proposed.
