Research On Design Method Of Array Transmitting Antenna For Microwave Wireless Power Transmission

Microwave wireless energy transmission technology is a high-power,long-distance wireless energy transmission technology,which has a wide range of application scenarios,and can realize a continuous wireless energy supply for electronic equipment in different application environments.The transmitting antenna part of the microwave wireless energy transmission system generally uses an active phased array antenna.The existing array antenna design method for obtaining high beam collection efficiency ignores design and engineering manufacturing difficulties brought about by improving the rectification efficiency of the receiving antenna part.In addition,there are few existing researches on microwave wireless energy transmission of moving targets.The impact of random errors on the efficiency of moving targets during energy transmission is also worthy of analysis and research.In view of these shortcomings,this paper has carried out research on design methods of array transmitting antennas for microwave wireless energy transmission.The main research work is as follows:(1)Approximately flat-topped main beam design of the transmitting antenna for microwave wireless energy transmissionAiming at the problem that the distribution of the microwave energy on the receiving rectifying antenna in the existing microwave wireless energy transmission system has a high center and a low edge,it is difficult to design a high efficiency rectifier.This paper proposes a design method of approximately flat-topped main beam of the transmitting antenna used in microwave wireless energy transmission system.This design method uses the least-squares curve to fit the aperture field distribution of the transmitting antenna,and aims at maximizing the beam collection efficiency and minimizing the mean square value of the power distribution in the receiving area.The beam collection efficiency of an approximately flat-topped main beam designed using this method can reach between 90%and 93%.While achieving high efficiency,the uniformity of the energy distribution in its receiving area is better than the case of 10d B Gaussian distribution and uniform distribution.(2)Analysis of beam collection efficiency during phased array transmitting antenna beam scanningThis section studies the effect of beam scanning on the efficiency of beam collection when the relative position of the transmitting and receiving antennas of the microwave wireless energy transfer system changes.First,the calculation formula of beam collection efficiency during beam scanning is derived.Then combined with the specific microwave wireless energy transmission scheme,the change of the beam collection efficiency,the center power density of the receiving area and the half-power beam width when the beam scanning angle is?_s(28)9 0??_s(28)0?2?4?6?8?10 in this case is analyzed.The numerical results show that from 0°to 10°,the receiving antenna shifted 9.698 meters from its original position.Beam collection efficiency dropped from 90.406%to 75.925%.The power density at the center of the receiving area also dropped from 34m W/cm~2 to 26.8178m W/cm~2.Beam width from 1.2502°to 22.6519°?It can be concluded that in microwave wireless energy transmission,beam scanning will cause the maximum gain of the radiated energy of the array transmitting antenna to be reduced and the main beam to be broadened,which will cause the beam collection efficiency to decrease.(3)Analysis of the influence of random errors on the efficiency of microwave energy beam collectionThe influences of random errors in the position of the transmitting antenna unit and random errors in the phase of the digital phase shifter on the microwave wireless energy transmission efficiency and the power density distribution in the receiving area during beam scanning are analyzed.Combined with specific case analysis,it can be seen that in the case of beam scanning at different angles,as the random error of the position of the array transmitting antenna unit increases,the beam collection efficiency and center power density in the receiving area gradually decrease,and at the same time the beam width becomes wider.Numerical results show that controlling the standard deviation of the random error in the accuracy of the array element position at???/60 can ensure that its adverse effect is low.If a 6-bit digital phase shifter is used and the standard deviation of the control phase error is??2?/2~6,its effect on the beam collection efficiency and the power density in the center of the receiving area is almost negligible.