| Microwave power transmission is an important issue in the development of human society.As a wireless power transmission method,microwave power transmission has a broad application prospect in space solar power stations,remote mountainous areas,canyons and Internet of Things devices because of its superior characteristics such as adjustable propagation direction,speed of light transmission,high-power and low propagation loss in free space.As an important part of the microwave power transmission system,the microwave energy receiving system will receive the microwave energy transmitted in free space and convert it into DC to supply the load,and its performance plays a key role in the efficiency of the microwave power transmission system,so this paper focuses on the key technologies of the microwave power transmission system,specific research includes.1.Study of high performance electromagnetic energy harvesting metasurface with wide angle.In order to overcome the problem of low reception efficiency of conventional receiving antennas and the inability to receive microwave energy efficiently at wide incidence angles,this paper designs a wide incidence angle high performance electromagnetic energy harvesting metasurface.Firstly,we analyze the working principle of the electromagnetic energy harvesting metasurface based on metamaterial theory and equivalent medium theory,and then design a two-dimensional window-shaped symmetric metasurface structure,which can achieve efficient electromagnetic energy harvesting at the resonant frequency of 10.15 GHz through the introduction of microstrip tuning lines and loading metallized vias at suitable locations.We further analyzed the effects of structural parameters,loading,and incident angle on the energy harvesting efficiency and resonant frequency of the hypersurface.The designed metasurface can collect microwave energy in the frequency range of 10.13～10.24 GHz with an incidence angle of 0～60° with an efficiency of more than 60%.When the electromagnetic wave is incident vertically,the maximum energy collection efficiency is 93%at the center frequency of 10.15 GHz,and the energy collection efficiency in the band range of 9.9～10.24 GHz is greater than 60%.2.X-band high-power rectifier circuit study.To meet the demand for high frequency and high-power wireless power supply,we design an X-band high-power rectifier circuit based on GAN diodes.Then,to further improve the rectification efficiency of the circuit,we designed a microstrip pass-through filter based on transmission line theory and implemented a multi-resonant pass-through filter by further optimizing it.The rectification efficiency of the designed rectifier circuit is greater than 60%in the input power range of 33 dBm 一 40 dBm,and the maximum rectification efficiency is 64.2%at the input power pin=40 dBm.3.Wide power,dual frequency high-power rectifier circuit study.In order to reduce the sensitivity of diode impedance to power and realize a wide power matching circuit,we have realized a rectifier circuit with a wide power incidence dynamic range of 36 dB by introducing a microstrip cascade rectifier topology.In response to the current research on dual-band rectifier circuits,which are mostly in the low-frequency and low-power direction,we designed a high-frequency and high-power dual-band rectifier circuit.First,we designed a broadband pass-through filter based on fan branching to widen the operating bandwidth of the pass-through filter.After that,we analyzed the effect of frequency on the input impedance of the circuit and introduced a microstrip cascade rectification structure to flatten the input impedance curve with frequency,and then designed a dual-band impedance matching network with series-connected microstrip lines to enable the rectification circuit to perform high-power rectification at 5.8 GHz and 10.15 GHz,and verified the circuit by practical tests.The maximum DC output voltages at 5.8 GHz and 10.15 GHz are 10.06 V and 6.74 V at an input power of 37 dBm. |
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