Experimental Determination of the Distribution of Current and Charge along Cylindrical Antennas

This paper describes an experimental arrangement to determine the distributions of current and density of charge along cylindrical antennas. Using a wavelength of 1.90 meters, the distributions are determined for center-fed straight cylindrical antennas of a diameter of 29 mm, and lengths of 1.25 λ, 1.00 λ, 0.50 λ. For the first two cases, the measurements are repeated when a center self-tuned parasitic antenna, of the same length and diameter as the driven antenna, is situated at a distance of 0.30 λ and 0.15 λ. The distributions are determined also on the parasite. To test the accuracy of the measurements and to relate the relative values of the current with the relative values of the density of charge, the distributions are determined on a coaxial line, having the inner conductor of the same diameter as the antenna under experiment, and fed at the same frequency as the antenna. A few comparisons with theoretical results are made.