**3.3 Antenna simulation**

Receiver antenna is a broadband type with linearly polarized radiation. Considering that our bandwidth is 500 MHz, according to previous experiences, we

**Figure 14.** *Output currents in 580, 650, 760 and 915 MHz.*

**105**

**Figure 17.**

*Measured and simulated reflection coefficients of UWB antenna.*

**Figure 16.**

*Designed U-shape UWB antenna.*

*RF Energy Harvesting System and Circuits for Charging of Wireless Devices Using Spectrum…*

require an Ultra Wide Band (UWB) antenna (**Figure 16**). By means of simulation and measurement, reflection coefficients of our designed antenna are indicated in **Figure 17**. Note that because of the size of this antenna, we did not use it obtain fabrication results. A challenge may be rise to decrease the size of UWB antenna

Test results for our fabricated charger circuit are indicated in **Figure 18**. In terms of experimental results, we obtain 6.89 V of output voltage at the frequency of 915 MHz (which obtained 8.8 V in simulation results), where our input signal is a 0 dbm generated by R&S®SMB100A signal generator. For a 10 kΩ resistive load, load

and improve our designed system performance in the future.

voltage is 2.12 V and we can calculate the output power as 450*μ* W.

*DOI: http://dx.doi.org/10.5772/intechopen.84526*

**3.4 Charger circuit fabrication**

**Figure 15.**

*Output voltages in 580, 650, 760 and 915 MHz.*

*RF Energy Harvesting System and Circuits for Charging of Wireless Devices Using Spectrum… DOI: http://dx.doi.org/10.5772/intechopen.84526*

require an Ultra Wide Band (UWB) antenna (**Figure 16**). By means of simulation and measurement, reflection coefficients of our designed antenna are indicated in **Figure 17**. Note that because of the size of this antenna, we did not use it obtain fabrication results. A challenge may be rise to decrease the size of UWB antenna and improve our designed system performance in the future.
