Design Of Digital Television Signal Energy Harvesting System

With the popularization of wireless sensor network in Internet of things technology,the shortage of power supply mode is widely concerned.The device collecting Radio-Frequency energy can make effective use of electromagnetic energy distributed in space,then realize the capability of wireless power supply.Therefore,in today’s application environment,it is of great significance to study the Radio-Frequency energy collection technology.This paper conducts the research and design of energy collecting system for Digital TV radio waves.Details are as follows:(1)A microstrip log-periodic antenna is designed for the digital television signal frequency band.The simulation results in HFSS software are good.In the working frequency band of 0.5-1.5GHz,the antenna can meet the requirement that the return loss is less than-10dB and the standing wave ratio is less than 2.and the maximum gain is 6.43.The maximum gain of the antenna is 6.45dBi.Therefore,it can be used as the receiving antenna of energy harvesting system.(2)A first-order rectifier circuit,made up of the HSMS285c rectifier diode and adopting the model of Dickson voltage doubler.Measurement results for the circuit show that 228mV can be generated across a 1.0kOhm from as little as-10dBm of input RF energy at 738MHz.The rectifier circuit realizes the function of RF rectifying at low input power.(3)Two DC-DC conversion circuit are studied.Measurement results show that the output of first circuit can be programmed to one of four fixed voltages in the low impedance input source.Another DC-DC converter can be matched with the rectifier circuit through the simple circuit and the output of circuit is a continuous pulse signal of which the peak voltage is 4.15V.By contrast,it is found that the latter is more suitable for RF energy harvesting system.(4)A data acquisition and receiving system,consisting of MSP430 temperature sensor module,433M wireless transceiver module and serial communication module,is constructed.Using a capacitor that charged to 4.15V as power supply,the system realizes the acquisition and transmission of temperature data.