Swept-frequency antenna gain measurements

This paper presents a method of making a swept-frequency antenna gain measurement which yields a result based upon the known gain vs. frequency of a standard antenna. This antenna consists of a 295-mm length of
X
-band waveguide with a cover flange on one end. It is an inexpensive and very satisfactory gain standard. The error analysis, which gives the accuracy of the resulting gain figure, consists of evaluating the conjugate mismatch losses at the antenna feed point or junction. This method of measuring gain is shown to yield useful gain data from an antenna test range that is not free of reflections. Gain vs. frequency curves are given for the standard gain antenna and a test antenna, having estimated accuracies of at least 0.27 dB and 1.00 dB, respectively.