Radio frequency energy is the energy transmitted by sources that can generate electromagnetic fields like TV signals, radio signal, wireless networks and cell phone towers, by using specially designed circuits connected to a an antenna this electromagnetic energy can be harvested and converted into a usable DC voltage. One of the applications of this technology is in radio frequency identification tags in which harvesting device can receives an RF signal from a sensing device; this RF signal can supply enough power to let the RFID tag to send radio frequency back including identification information to any item of interest. The circuits designed for such applications can made relatively small and can convert the ambient electromagnetic
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For this reason there has been a significant interest to develop a completely self-powered WSN. A Dynamic Power Management System (DPM) has been equipped to most WSN. The purpose of DPM is to conserve energy and that is achieved by shutting down parts of the WSN which are not used or active. Such devices can be powered from RF sources belonging to an existing wireless network or system. Low profile high gain antennas are usually used and configured by using slot radiators. There is one drawback to this approach which the narrow frequency bandwidth limits used in those applications. This drawback can be overcomed by the use of high gain receiving antenna resonating at 2.44GHz, rectifier and a power management circuit.
We can improve the bandwidth of antennas by using gap coupled parasitic patches. In the design proposed here consists of two additional patches on the ground plane as shown in the figure below. Doing this would improve the return loss of the antenna while keeping the thickness of the substrate as low as possible and maintaining the simplicity of the overall structure. The antenna is designed of 1.575mm thick Rogers RT5880 substrate with ε = 2.2, tan δ = 0.0009, and copper metallization a 0.2mm. The antenna was designed with of λ/2 = 42mm and