Wireless Power Transmission

A New Circularly Polarized Rectenna for Wireless Power Transmission and Data Communication
Small distributed wireless sensors are becoming very important in many aspects of our lives. While low data rate passive sensors operate with little energy there is a need for moderate to high data rate distributed sensors for infrastructure monitoring and other applications. Such sensors will require their batteries or onboard capacitors to be charged when depleted for proper operation. In this letter, we propose a circularly polarized (CP) microstrip patch antenna that can function as a WLAN antenna in the 5.15–5.35 GHz and as a rectenna at 5.5 GHz. RECENTLY, considerable emphasis has been placed on studying the quality and safety issues of our nation’s transportation infrastructures. A careful evaluation of the life span and current condition of steel reinforcement tendons inside the concrete covering of a bridge is crucial to ensure public safety. The solution for this problem calls for the deployment of miniaturized embedded sensors within the bridge structure itself during the construction process. An RFID (radio frequency identification) type passive sensor utilizes a narrowband tank circuit. Thus, the presence of other metallic objects can cause a significant frequency shift as a result of which the sensor may not operate properly. Also, due to the availability of low power, only a very limited amount of data transmission is possible. In contrast, a 5–6 GHz WLAN type sensor is not limited in data rate and does not have the constraints of a narrowband LC tank circuit. However, for proper functioning of the circuitry there must be a mechanism to: 1) remotely charge the transceiver battery or capacitor as needed, and 2) send and receive data in between the embedded sensor and the interrogator.

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