Research On Rectenna For Ambient Microwave Energy Harvesting

With the development of the communication information industry,the resources of electromagnetic waves in space are becoming ever more abundant,and the collection of microwave energy in space has also received extensive attention in the industry.At the front end of the space microwave energy harvesting system,the rectifying antenna is responsible for collecting electromagnetic energy in the space and converting it into DC energy for low-power DC load.An ultra-wideband planar spiral antenna and multi-band rectifier circuit for the front end rectifying antenna applied to the space energy harvesting system was designed and fabricated,and the testing of each part was done.The specific work content is as follows:(1)An ultra-wideband receiving antenna working at 1.5-6.0 GHz is intended for the GSM1800,3G,WiFi and Bluetooth bands 5.8 GHz used in the communication band.Compared to a single-frequency signal source,The collected microwave energy is more and the output voltage is relatively higher.Therefore,the antenna structure is intended to be an ultra-wideband planar spiral antenna,and it is simulated and optimized in the electromagnetic simulation software HFSS.The performance of the antenna is enhanced by loading the shaped reflector and the end absorbing resistor,and finally the physical production is completed.The actual measurement results are below-10dB in the full frequency band,and the directivity is good,and the maximum gain is about 7.8dBi.(2)Under the condition of input-10dBm signal power,two kinds of rectifier circuits are designed:one is the 1.8-2.1 GHz wideband rectification circuit in the working frequency band,and the optimal load is chosen.After the simulation design is accomplished by the RF circuit simulation software ADS,Make the actual object and test it.The measurement results show that S11 is below-lOdB in the rectification frequency band,the output DC voltage range is 149-174mV,the rectification efficiency is 14.8%-20.2%,and the other is the dual frequency rectification circuit with the operating frequency of 2.45GHz/5.8GHz.The voltage across the load resistor is 73.8mV and 10.1mV respectively.,respectively,and the rectification efficiency is 10.2%and 3.8%.(3)On this basis,the two rectifier branches are integrated,and the input port and the output port are integrated in parallel and series,respectively,finally integrated with the antenna.The rectifying antenna is tested in the vicinity of the mobile communication base station antenna and the WiFi ceiling antenna.The voltage across the load resistor is 73.8mV and 10.1 mV respectively.The designed rectenna can achieve the purpose of spatial microwave energy collection.