Research On Miniaturized Millimeter Wave Broadband Antenna For Electromagnetic Energy Collection

As an emerging technology for green communication,electromagnetic energy harvesting technology can convert electromagnetic energy,which is usually regarded as interference,noise and other unfavorable factors,into exportable electrical energy through electromagnetic energy receiving devices for charging low-power devices.At present,electromagnetic energy harvesting is mainly through the mode of receiving antenna plus rectifier circuit to convert electromagnetic energy into DC output,and most of the academic researches focus the working frequency band of rectifier antenna on microwave band,such as L-band,S-band and C-band,which cannot meet the future demand for electromagnetic energy harvesting in 5G millimeter wave band and 6G communication band.In addition,most of the research work on microwave rectenna only focuses on a few common communication frequency points,such as1.8 GHz,2.45 GHz and 5 GHz,which will be disjointed with the future era of high frequency,large broadband and high-speed information transmission.In response to the above problems,the work in this thesis focuses on the research of miniaturized millimeter wave broadband rectifier antennas,and designs two practical broadband antennas and a broadband rectifier circuit,the main research and innovative work are as follows:I.A miniaturized millimeter wave broadband array antenna based on hierarchical structure is proposed.By layering broadband patch antenna and feed network separately,the distance between patch radiation units is effectively reduced.With the help of HFSS(High Frequency Structure Simulator)electromagnetic simulation software,the 4×4 array antenna design was realized.The array antenna achieves a VSWR of less than 2 in the 21.8-27.0 GHz band and a maximum gain of 9.1 d Bi in the central direction in the impedance bandwidth.II.A flexible conformable broadband antenna is designed based on the surface wave structure,and the initial model is optimized with the help of HFSS electromagnetic simulation software to improve the operating bandwidth of the antenna.The simulation results show that the flexible antenna generates dipole-like radiation mode in the case of 90° bending conformal.The return loss band of-10 d B covers 10-20 GHz,the relative bandwidth is up to66.7%,and the radiation efficiency in the band is up to 82%,which has good broadband and radiation characteristics.III.The performance analysis of commonly used rectifier diodes is carried out.With the help of ADS(Advanced Design System)circuit simulation software,three types of rectifier circuits are simulated and compared,and finally the single-tube parallel rectification method is selected to realize the design of millimeter-wave rectifier circuit for 22-27 GHz.The rectification efficiency of the rectifier circuit is between 40% and 60% in the operating band at an input power of 21 d Bm.Finally,the innovation and research problems solved in this thesis are summarized in detail,and the development trend and application scenarios of space electromagnetic energy receiving technology are prospected.