In today's world, where almost all aspects of life will be carried out wirelessly, the concept of wireless electricity is interesting for modern technologies where electricity is distributed without interconnecting wires. This concept can be considered as a new alternative energy supply, especially for small powered electrical and electronic equipment. By exploring the concept of wireless electricity, new approaches can be developed to apply the concept economically and user-friendly.
The aim of this project is to research a suitable concept of wireless electrical transmission in a living room. The concept will be applied to low-power electrical devices, such as charging rechargeable batteries and lighting a lamp.
Objectives and Scope of Study
Radio Frequency (RF) Signal
However, these radio waves do not interfere with each other because each RF transmission broadcasts at different frequencies. The frequency is chosen as it falls under Industrial-Scientific-Medical (ISM) RF band range (902 MHz - 928 MHz), made available by the Federal Communication Commission (FCC) for low-power and short-range experiment. In addition, the use of the frequency does not need permission from the authority, since it is not used by other applications such as radio transmission, Bluetooth, hand-phone communication and TV broadcasting [3, 4).
Project Progress ......................................................................... l1
Although there are some problems in the middle of the progress of the project, the problems have been solved and the project is back on track. Please refer to Appendix III and Appendix IV for Project Milestone and Project Gantt chart, respectively. Data and information related to circuit design are generally from the theoretical part, which includes some calculations.
Other information in the design of the circuit is observed from the simulation and prototype test results.
For the simulation of the improvement parts, some tests are done to check the performance and improve the output of the circuit. By doing this, the input of the receiver is connected to the power supply to receive the AC voltage. Although the increase in output voltage was decreasing, it is acceptable since the decrease is predicted theoretically.
Building on the current design, the number of stages was increased to eight stages to test whether the output voltage pattern continued. From this it was decided to increase the value of the capacitor to a higher value. To test the performance of the new circuit, the capacitor value was again increased to 330 j.IF.
Schottky diode (1N5819) - diode performance is proven in voltage amplification and rectification. As can be seen from Figure 2, there was no external antenna, as the antenna was printed on the back of the board (Printed Antenna). The test was done to test the performance of the prototype in gathering electromagnetic energy in the air.
In this test, the antenna was connected to the input of the prototype and replaced the AC power supply. The output of the receiver was connected to the voltmeter to measure the output voltage that could be produced. The proposal from the first part was integrated into the second part of the test.
Because of this unexpected result, the receiver circuit was redesigned and a germanium diode was installed instead of the schottky diode. We connected the redesigned circuit to the antenna and observed its operation of the first phase. Using the results of the previous test (energy recovery test), a fmal prototype of the receiver was built.
From the result, it clearly showed that the signal energy generated by the transmitter was collected, rectified and amplified by the receiver circuit to produce DC voltage. For the application part, the DC output of the receiver was connected to a battery charging circuit.
Like the first test, it was due to the charging time of the capacitor where lower value capacitor had faster charging time compared to the higher value capacitor. From the result it could be observed that the receiver did not deliver the expected result where the output voltage is only around 12 to 13 V instead of 67 V (from simulation). Checking the condition and the components of the circuit, the source of the problem was due to the rating of the capacitor where the voltage rating is 12V.
By revisiting the circuit design and voltage doubler theory, the source of the problem was identified. Based on the state of the circuit, it was determined that the problem was due to the value. In fact, this value was better than the predicted result, which is 70 V. From the results of all the tests, it could be concluded that the rated voltage of the capacitor, the types of diodes and the value of the capacitor play an important role in determining the output value of the receiving circuit.
From the results of all the tests done, it could be concluded that the germanium diode receiver was good at collecting electromagnetic energy, but not very good at amplifying the received signal to the maximum. For the operation of the application circuit, it started with the transmitter transmitting the signal to the receiver. A switch was used to switch the battery connection between the charging circuit and the output application.
To improve this, further research is needed, especially on the integration of both germanium diodes and Schottky diodes into the receiver circuit. Further research is needed, especially on integrating both types of diodes into the receiver so that both diode benefits can be optimized by the receiver circuit. What it means by circuit minimization is that the circuit of the receiver and the transmitter is minimized as much as possible.
The shapes and sizes of the antenna depend on the frequency the antenna is trying to receive. The size of an optimal radio antenna is related to the frequency of the signal the antenna is trying to transmit or receive. In one cycle of the sine wave, the transmitter will move electrons in the antenna in one direction, switching and pulling back, switching and pushing out, and switching and moving back again.
In other words, the electrons will change direction four times during one cycle of the sine wave. Changing the capacitor changes the resonant frequency of the resonator and thus changes the frequency of the sine wave that the resonator amplifies.
CONCLUSION AND RECOMMENDATION
Based on the electromagnetic spectrum, RF waves range from 3 kHz to 300 GHz and the wavelength varies for each frequency based on the equation: speed of light (c)= Frequency (t) X wavelength (/.). It is used to measure the amount of RF energy absorbed by the human body and the potential harm it can cause. As long as the exposure is not too high or moderate, it is allowed to extend the exposure time for a short period.
Project Gantt Chart
Antenna & Resonator
The sine wave corresponding to that specific frequency is amplified by the resonator and all other frequencies are ignored. From this it can be concluded that the value of both the capacitor and the inductor have an effect in determining the resonant frequency.