抛物面圆反射器天线功率密度的计算程序

PROCEDURE FOR CALCULATINGTHE POWER DENSITY OF APARABOLIC CIRCULARREFLECTOR ANTENNA Herbert K. Kobayashi U.S.DEPARTMENTOFCOMMERCERobert A. Mosbacher, Secretary JaniceObuchowski,AssistantSecretaryfor Communications and Information FEBRUARY1990 ABSTRACT This technical report details a procedure for calculating the mainbeam off-axis powerdensity in the near- and far-field of a parabolic circular reflector antenna. In this report, theon-axis procedures of NTiA TM-87-129 and its IBM-PC compatible Antenna Field Intensity (AFl)program are extended to off-axis analysis. Like its predecessors, it is intended for general usein system planning and evaluation and gives a worst-case estimate for radiation hazardassessment. The procedure starts with the on-axis power density at a given distance obtained from theTM-87-129 report or AFi PC program. This is multiplied by the normalized near-field powerdensity for the chosen off-axis angle to give a final answer. The simple log-function form of the normalized curves lends itself to inclusion in theautomatedAFlprogramasa computeralgorithm. The method chosen for developing the procedure is general and may be applied to otherdirective antennas provided sufficient near-field off-axis data are available. KEYWORDS AntennaFieldIntensity(AFl)ProgramNear-Field Off-axis Power DensityOn-axis Field IntensityParabolic Reflector (Circular) TABLE OF CONTENTS SECTION 1 INTRODUCTION BACKGROUND1-1OBJECTIVES1-2APPROACH1-2 SECTION 2 SUMMARY AND RECOMMENDATIONS SUMMARY2-1GENERAL CONCLUSIONS2-1 SECTION 3 PARABOLICCIRCULARAPERTUREANALYSIS INTRODUCTION3-1APERTUREDISTRIBUTIONANDD/X.ASPARAMETERS3-1DEVELOPMENTOFAPROCEDUREFOROFF-AXISCALCULATIONS3-3Approach3-3Power Density inthe Near-Field3-4Source 1: Hansen and Bailin3-4Source 2: ECAC Handbook3-5Source 3: Lewis and Newell3-9Small-Aperture Near-Field Power Density3-16Effect of LargerDish Sizes and Aperture Pedestals. 3-18Derivation of Relative Power Curves of the Procedure3-18 TABLE OF CONTENTS(Continued) SECTION 4 PROCEDUREFORCALCULATINGTHEPOWERDENSITYOFAPARABOLIC CIRCULARREFLECTORANTENNA4-1INTRODUCTION4-1GENERALPROCEDURE4-1STEP 1. Determine the on-axis power density for a circularaperture antenna at the desired distance4-1STEP 2. Find the input parameters for the off-axis procedure4-2STEP 3. Look up the relative power density"correction"4-2STEP 4. Combine the on-axis power density and the "correction"4-2WORKEDEXAMPLE4-3Step-by-step procedure4-3Comments on example4-3 APPENDIX AFI COMPUTERALGORITHMS FOR POWER DENSITY CURVESA-1 REFERENCES R-1 LIST OF TABLES TABLE 3-1CIRCULAR APERTURE CHARACTERISTICS FROM SILVER3-23-2PARAMETERS OFTHEPOWER DENSITY CURVES3-25 TABLEOFCONTENTS(Continued) LISTOFFIGURES FIGURE 3-1Circular aperture illumination as a function of n3-33-2Relative fieid intensity vs mainbeam off-axis anglen = 0, D = 10), simplified after Ref. 143-63-3Relative power density versus off-axis anglen = 0, D/> =10,based on data from Figure 3-13-73-4Power dispersion curves,n =0Taken directly from Fig.5-34,Ref.153-83-5aRelative power density vs mainbeam off-axis anglen = 0, D = 10), based on data from Ref. 153-113-5bRelative power density vs mainbeam off-axis anglen = 1, D = 10), based on data from Ref. 153-123-5cRelative power density vs mainbeam off-axis anglen = 2, D = 10), based on data from Ref.153-133-5dRelative power density vs mainbeam off-axis anglen = 3, D = 10), based on data from Ref. 153-143-6Relative power density curves in the Y-Z planen = 2, D = 10), directly from Fig. 6, Ref. 103-153-7Relative power density vs mainbeam off-axis anglen = 2,D = 10), based on data from Ref.103-173-8aRelative power density vs mainbeam off-axis anglen = 2, D = 30, based on data from Ref. 103-193-8bRelative power density vs mainbeam off-axis anglen = 2, D = 30), -20 dB pedestal, data from Ref. 103-203-9aRelative power density vs mainbeam off-axis anglen = 0, D =30),based on data from Ref.153-213-9bRelative power density vs mainbeam off-axis anglen=1,D =30),basedondatafromRef.153-22 TABLE OF CONTENTS(Continued) LISTOFFIGURES Page FIGURE 3-9cRelative power density vs mainbeam off-axis anglen = 2, D = 30), based on data from Ref. 153-233-9dRelative power density vs mainbeam off-axis anglen = 3, D = 30, based on data from Ref. 153-243-10aRelativepower density curvesD/> < 30, n < 0.53-263-10bRelative power density curvesD/> < 30, 0.5 ≤ n < 0.53-273-10cRelative power density curvesD/> < 30, 1.5 ≤ n < 3.53-283-10dRelative power density curvesD/>≥30, n < 0.53-293-10eRelativepowerdensitycurvesD/>≥ 30, 0.5≤ n < 1:53-303-10fRelativepowerdensitycurvesD/> ≥ 30, 1.5 ≤ n < 3.53-31A-1Pathway for selection of a normalized density curvebased on TABLE 3-2A-2A-2Generalized relative power density curveA-3 SECTION 1 INTRODUCTION BACKGROUND The National Telecommunications and Information Administration (NTIA) is responsible formanaging the Federai Government's use of the radio frequency spectrum.NTIA'Sresponsibilities include establishing poli