## 6 Experimental Verification
After flowing through the detection circuit and the envelope circuit, the signal is sent to the comparator and amplifier circuit. Then, the demodulation module extracts the information encoding. Finally, the information-encoded square waves are obtained. Figure 14(a) shows the process of only forward information transferring without power transmission and the communication rate is 20 kbps. \(V_{T3}\) is the modulation signal source for the forward information transfer. \(V_{rs}\) is the voltage of \(R_{d2}\). \(V_{HPF}\) is the output voltage of HPF. After HPF, the low-frequency power waves and other harmonic are filtered out. Then, the envelope detector will follow the peak voltage of \(V_{HPF}\) and its output voltage is \(V_{ENis}\). Finally, the forward information transfer signal will be demodulated by amplification and comparison. \(V_{os}\) is the output voltage of forward information demodulation cell. Similarly, the process of only backward information transferring without power transmission is shown in Figure 14(b). \(V_{T4}\) is the modulation signal source for the backward information transfer. \(V_{rp}\) is the voltage of \(R_{d1}\). Contrary to forward information transfer, the structure of demodulation cell for backward information transfer uses BPF to pick  
Figure 14: Measured output voltage and current waveforms when the power transmission direction is switched. Figure 15: The forward and backward information transfer with no power transfer. (**a**) Only forward information transfer. (**b**) Only backward information transfer. up the selected signals. \(V_{BPF}\) and \(V_{ENp}\) are the output voltage of BPF and envelop detector, respectively. \(V_{op}\) is the output voltage of backward information demodulation cell. According to the experimental results, the information transmission is realized correctly. In Figure 16a,b, the simultaneous wireless information and power transfer is implemented successfully and the communication rate is 20 kbps. The forward and backward information are injected into the power carrier through the modulation signal source in the primary and secondary sides, respectively. Then the waveforms are received at the secondary and primary sides to achieve the demodulation process. Compared with only information transfer, power transmission interferes with the information demodulation, the information can still be received correctly through information demodulation cells. Figure 17a presents the process of simultaneous bidirectional information transmission if there is no power carrier in the circuit. \(V_{73}\) and \(V_{74}\) represent the output voltage of tight coupled transformer in primary side and secondary side, respectively. \(V_{rd}\) and \(V_{rs}\) represent the received high-frequency signal and the filtered information signals, which means the information transmission is completed via a shared channel. \(V_{op}\) and \(V_{os}\) are the information waveform obtained from the demodulation circuit in both sides. According to these experimental results, the forward and backward information can be transmitted simultaneously and independently. Similarly, Figure 17b verifies the simultaneous transmission of forward and backward information, the results indicate  
Figure 16: The forward and backward information transfer with power transfer. (**a**) Only forward information transfer. (**b**) Only backward information transfer. Figure 17: The full-duplex communication between the primary side and the secondary side. (**a**) Power carrier does not exist in the circuit. (**b**) Power carrier exists in the circuit. that information can still be transmitted and demodulated if there is a power carrier in the circuit. In short, the influence of information carrier on power transmission can be ignored during power transmission; similarly, during information transmission, regardless of power transmission, information can be transferred in full duplex mode.