Design And Experimental Research Of Antenna Measurement System Based On An UAV

In order to solve the problem that the antenna in their operative conditions is difficult to be measured,this paper presents a measurement method based on small unmanned aerial vehicle(UAV)platform.The measurement system is designed and verification experiment is carried out.According to the antenna far-field pattern measurement principle,an antenna far-field measurement method based on UAV platform is proposed.This method is that the UAV carries the test signal source to move and the antenna under tested(AUT)is fixed.The overall scheme design of the measurement method is carried out,which includes the UAV platform,the posture measurement equipment,the signal transmission front-end subsystem(including the signal transmitting antenna),and the signal receiving subsystem.The key technologies and difficult problems such as positioning accuracy,data matching,signal front-end lightweight and electromagnetic compatibility are analyzed.For performance requirements analysis,the DJI M600 PRO small-rotor UAV and the GPS-RTK(real time kinematic)system with centimeter-level accuracy were selected as the measurement platform and pose measurement subsystem respectively.According the system link estimation,the RF signal source,filter,amplifier and other RF devices at the front end of the signal are selected and designed respectively.After testing,signal front end meets system measurement requirements in the frequency range 650MHz-1200MHz.Signal front end shield box has good electromagnetic compatibility.Aiming at the design of high frequency,broadband and lightweight of the transmitting antenna based on the far-field measurement of the UAV platform,the design and optimization of the single dipole antenna and the reflective cavity dual-polarization dipole with reflective cavity antenna are studied.Both the simulation and the measured results show that the single dipole antenna has uniform directionality,and the gain is 2.2dBi and 3dB beam width is 79.1°at 750MHz.The double dipole antenna adopts the"copper foil+PA6" lightweight design,and the voltage standing wave ratio(VSWR)is less than 2.5,the gain is greater than 7dBi in 650MHz-1200MHz and the pattern symmetry is good.Correspondingly,designed and produced the mounted structure of the UAV for the signal front end.The weight of transmission subsystem is 1.29kg,and the whole unit of the total load on the UAV(including the GPS-RTK sky end)is 1.54kg to meet the design requirements of the UAV extended load within 3kg.Finally,research work on the design of verification experiments,AUT preparation and simulation,measurement data processing methods,and verification experiments were carried out.The verification experimental results illustrates that the system can effectively measure the radiation characteristics of antenna pattern.Compared with the simulated pattern,the main lobe and side lobe morphology are consistent,and the causes of the positional deviation of the amplitude and pattern are analyzed.The antenna measurement system and its experimental results designed in this paper provide a new idea and method for antenna measurement,and lay a vital theoretical and design foundation for the next step of antenna engineering system research and development.