Nowadays CDMA and GSM modem technology are still widely used by the community, especially in rural areas and small towns that are quite far from the BTS location. This paper designs the Yagi-Uda antenna for CDMA modems on the 800 MHz frequency. The number of elements used is 1 driven, 1 reflector and 16 directors. The antenna design simulation uses NEC-Win Pro 1.6 and Ansoft HFSS 13.0 software. Simulations using NEC-Win get VSWR values 1.59 and S11 -13 dB (uses Matlab). Next, the simulation using Ansoft HFSS obtained the results of VSWR 200000 and S11 -9 dB. The simulation results also show that antenna design already has a directional radiation pattern.
The potential for hybrid combinations using solar and wind energy can be found in several places, one of which is on the highway. Highways are open areas exposed to direct sunlight and wind can blow forming natural wind tunnels. In addition, vehicles that pass on the road also generate wind which can then be used as an energy source. The purpose of this study is to find out how significant the potential for hybrid energy is by utilizing a combination of solar energy and wind energy obtained from utilizing traffic flow. The method used in this study is an experimental method by testing how much energy is obtained from sunlight by using a solar cell 50 Wp and wind energy by using a technological innovation Veritkal Axis Wind Turbine (VAWTs) 300 watts as a producer of electric power on the highway by utilizing two types of wind at once, namely atmospheric scale wind that blows naturally and wind from vehicle traffic on the highway. Current, voltage, and power measurements are then measured using a digital watt meter. The study's results found that the combined potential of solar energy and wind energy obtained from utilizing traffic flow was 552.11 watts, greater than just using a naturally blowing engine with a power of only 498.67 watts. This energy difference occurs due to an increase in wind frequency generated by traffic flow by 22%.
Nowadays, the research about the harvesting of renewable energy sources is more interesting on being able to do the conversion and conservation of thermal energy source, which is very abundant in our environment especially in form of waste heat. The abundance of waste heat energy in our daily life is needed to be converted to become something useful like electrical energy. The research about a material called metamaterial in the form of thermal concentrator has shown the capacity for focusing heat flux into a specific area. Optimized flower-shaped metamaterial thermal concentrator design is successful to concentrated the heat flux from any direction to specific area efficiently. This research is about numerical analysis of harvesting thermal energy to become DC electrical energy by using a design of metamaterial thermal concentrator, especially the design of optimized flower-shaped metamaterial concentrator by using the thermoelectric device. The result showed that with using optimized metamaterial thermal concentrator can increase the output voltage of thermoelectric device become 4,1 volt, compare than without using the concentrator that just gets output voltage 3,3 volt.
The paper proposes the design of a power supply circuit for charging drone batteries using thin-film solar cells. Thin-film solar cells are arranged in parallel to produce a fixed voltage and a large enough current to be able to charge the battery drone. Each output of the solar cell is connected with a step-up device so that the voltage rises to 5 volts. Then all the output from the step-up will be inserted into the power booster supply so that the voltage rises to 28 volts. The unique form of thin-film solar is lightweight and flexible, so the power plant will be placed right above the frame of the drone. The goal is that sunlight can be directly received by the top layer of the solar cell to be converted into voltage. The design of this power supply circuit is expected to be able to increase the length of the drone’s flight in the air.
Energy demand increases in line with rapid technological advances. Research on the harvesting of renewable energy continues to be done to make efforts to convert heat energy, which is very abundant in our daily environment. Thermoelectric technology is an alternative source in answering energy needs and can produce energy on a large and small scale. Thermoelectric technology works by converting heat energy into electricity directly, or from electricity to cold. This research presents an experimental study conducted to find out the thermoelectric characteristics of the TEC in the reversal function, with heating and cooling tests on each side of the TEC type thermoelectric element, carried out to obtain the voltage value as the electrical potential generated from this element. The result is thermoelectric potential to generate DC electricity but is very limited in the function of maintaining a heat source on the hot side element. This research then proposes thermal metamaterial that functions as a collector of thermal energy in the method of converting thermal energy into DC electrical energy for the application of low power consumption communication systems.
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