Discussion of errors in gain measurements of standard electromagnetic horns.
Robert William Beatty · 1967
In setting up a calibration service for measuring the gain of standard electromagnetic horns, one needs a reference horn in which one has developed a high degree of confidence.Although it is possible to calculate the gain of horns of certain design, confidence can be increased by carefully measuring the gain.This note examines a method for measuring the gain of two identical horns, listing the assumptions made in making such a measurement.The theory of 2 -port waveguide junctions is applied to the analysis of the measurement technique.The method is shown to be essentially an attenuation measurement which has additional sources of error.Although these errors are not analyzed and evaluated in this note, the problem is perhaps more clearly stated than it -was previously.The mis- match error in comparing two horns as receiving antennas is analyzed.Data is given on the aperture efficiency of standard horns which indicates that improvements in the design of such horns are feasible.It is concluded that, at present, an uncertainty limit of the order of tenths of decibels seems realistic, but hundredths of decibels seems unattainable until further refinements are made both in the standard horns themselves and in the measurement techniques.