On The Error Analysis And Correction Techniques Of Planar Near-Field Scanning For Ultra-Low Side-lobe Antenna Measurements

ABSTRACTttis dissertaion deals with the ermr analysis and correchon techniques of planarnear field scanning for ultra-low-side-lobe antennas measurementS. First, the errors causedby the various ermrsources are equivaleflt to the amplitude and phase errors of the datameasured in the near field plane. For simplicity the amplitude and phase distribution ofantenna under test (AUT) on the grids in the near-field sctring plane is equivalent to thedistriblltion on an antenna array The expressions of side-lobe measurement errors versusthe relative parameters of AUT are presented when ultra-low-side-lobe antermas are testedby the planar near-field measurements. The error-uPper-botmds expressions of antermaspallem ermrs resultCd frOm the finite scanning truncation errors, position errors,instoentation errors, multiple-reflection errors and measurement environrnent errors innear filed measurement are derived respectively. Then, the effect of some main errorsources in near field measurement on the side-lobe of ultra-low-side-lobe antennas patternare simulated by computer simulation method. Finally the effective methods fOr thoseerror sources to be reduced are made with computer simulation and the "self correction"method for the errors produced by multiple-reflection and environment to be reduced areproved with the experiment. The dissertation is divided into 6 chapters. The main contcntsof these chapters are as follows:ChaPter l is Preface. The principles of planar near field measurement are introduced inthis chaPter. The ari-states and history of the near field measurement tecImiques arereviewed systematically. The measurement of ultra-low-side-lobe antennas by the planarnear field technique is outlined and the significance of this research prOject is surveyed.The studied works and the diagrarns of this dissertation are also given.ChaPter 2 is The Basic Theory The relative mathematical formulations used in thedissertation are listed, which include the relative mathematical theory in advancemathematics, engineering mathematics, probability and statistics, error theoryelectromagnetic theory and the theory of near field anenna measurement.ChaPter 3 is The Main Error-UpperBounds Analysis of Near Field MeasurementTecdriques for Ultra-Low-Side-lobe Anennas Measurements. There are 8 Sections in thischaPer. The expression of the side-lobe measurement errors versus the relative parametersof AUT is analyzed when the ultra-low-side-lobe amennas are tested by the planar-near-field measuremellts. The ermr-uPper-bouhds evaluaion expressions of the amermas pattemerrors, caused by the trite scanning trUllcation errors, POsihon ermrs, inientationvlIerrors, multiple-reflection errors and measurement environment errors in the near filed measurement, are derived respectively, and these expressions are explained and discussed.Chapter 4 is Main Errors Simulation for the Ultra-Low-Side-Lobe Antennas Tested by Near Field Measurement Techniques. First, the mathematical expressions are deduced for simulation processes. Then, the effect of the total AUT amplitude and phase errors m the near-field scanning plane, the finite scanning truncation errors, position errors, instrumentation errors, multiple-reflection errors and the measurement environment errors on the side-lobe of the ultra-low-side-lobe antenna patterns are qualitatively analyzed by computer simulation method.Chapter 5 is The Computer Simulations Method for the Main Errors Correction of the Ultra-Low-Side-Lobe Antenna Tested by Near-Field Measurements. The simulation of the errors correction methods are made for the errors resulted from the AUT amplitude and phase measured errors on the scanning plane, the finite scanning truncation errors, position errors, and instrumentation random errors in the near field on the mathematical models given in Chapter 4 and the simulation results of the errors correction methods are given.Chapter 6 is Method for the Multiple-reflection Errors an...