Research On Dual Polarized Rectennas For RF Energy Harvesting

The arrival of the 5G era has brought greater opportunities to the development of the Internet of Things(Io T)devices.The limitation of battery power supply capacity has become the main bottleneck restricting the development of wireless devices.Compared with the electromagnetic induction,microwave power transmission(MPT)has become an appealing method to supply power for multiple portable electrical devices because of its advantages such as long transmission distance.The rectenna is the most critical component of the wireless power transmission system.And the study of a high-efficiency rectenna plays a vital role in the entire system.Taking into account the 5G requirements for MIMO antenna technology and the ability of more multi-polarized antennas to capture electromagnetic waves of multiple polarizations in space,this paper mainly focuses on dual-polarized rectenna,which can improve the upper limit of the input power of the rectenna.The dual-polarized receiving antenna,rectifier circuit,and receiving antenna array all have innovative improvements.The main research contents are as follows:Firstly,a dual-band dual-polarization rectenna is proposed.The dual-polarization receiving antenna and dual-band rectifier mainly operate at 2.45 GHz and 5.8 GHz.The receiving antenna adopts coplanar waveguide(CPW)and microstrip line,which can ensure high isolation of more than 20 d B in both operating bands,while the cross polarization is less than-15 d B.The ?-shaped topology is introduced to the network for realizing accurate impedance matching at both bands simultaneously.After simulation and measured,the proposed antenna works well at the two ISM bands(2.45 and 5.8 GHz)with a-10 d B impedance bandwidths of 290 MHz(2.39-2.68 GHz)and 920 MHz(5.16-6.08 GHz).After testing,the maximum microwave-direct current(mw-dc)conversion efficiencies of 67.7 %and 57.03 % at 2.45 GHz and 5.8 GHz are achieved with a 300 ? load and 16 d Bm receiving power.Secondly,a dual-polarized rectenna unit based on coaxial feeding is designed.The antenna works at 2.45 GHz.In order to capture more RF power in the process of wireless power transmission,a 2×2 array design is completed on the basis of the rectenna unit design.It mainly uses a one-four power divider to combine the power captured by the four units of the receiving antenna.Finally,measured tests show that peak microwave-direct current(mw-dc)conversion efficiencies can reach 69.1 % with a 800 ? and 10 d Bm imput power.Finally,a aperture-coupled 2 × 2 dual-polarized rectenna array is designed.And the rectenna also operate at 2.45 GHz.The receving antenna array adopts a aperture-coupled feeding method integrated on the bottom layer of the substrate.Compared with the last chapter,the structure is more simple.The receiving antenna array has three ports,and the vertical polarization port and the horizontal polarization port can obtain-10 d B bandwidths of16 % and 20.3 %,respectively.In addition,the rectenna array can achieve a maximum efficiency of 63.02 % with the input power Pin = 10 d Bm and RL=1000 ?.