"The development and widespread use of radar systems in World War 11, and the post-war television boom, has brought about a large amount of investigation in antenna arrays. One of the types of antennas commonly used on radar systems during the early part of the war, and one which finds wide usage today as a television receiving antenna, is the well known Yagi antenna...
Since television antennas are usually mounted out of doors, the antenna must be made mechanically strong to prevent whipping or twisting due to wind, and to prevent sagging due to icing or to its own weight. These precautions are necessary since if any of the antenna elements are twisted or sag, such that they are not all parallel and in the same plane, currents may be induced in the elements which do not have the proper phase relationship and "ghost reception” will result.
Due to the necessity of this mechanical strength it is common practice in the manufacture of this type of antenna to mount the elements solidly to a metallic crossbar. This crossbar being in the near field of the antenna array will experience an induced current and will act as an antenna element. It was the purpose of this experimental investigation to study what effect the placing of this metallic crossbar across the antenna elements had on the current distribution along the antenna elements, and on the radiation pattern of the whole antenna array. "While it might be assumed that some investigation of this problem must have been done by the manufacturers before putting this type of antenna into production, a check of the available literature indicates that very little work has been done along this line. Considerable work has been done in recent years by other persons interested in current distribution along various types of antenna elements, but none of these investigations were directly applicable to the particular problem at hand. However, some of the results of the previous work could be used in evaluating the results obtained in this investigation, and that material will be discussed at the proper place in this thesis giving due credit to the proper investigators.
From the standpoint of antenna theory it is desirable to know the current distribution along the antenna elements, since if it is known, the radiation pattern and the input impedance of the antenna system can be found, contingent only upon the ability of the person making the investigation to perform the various integrations that will be encountered"--Introduction, pages 1-3.
Skitek, G. G. (Gabriel G.)
Electrical and Computer Engineering
M.S. in Electrical Engineering
Missouri School of Mines and Metallurgy
vi, 83 pages
© 1952 Gerald F. Sinnamon, All rights reserved.
Thesis - Open Access
Antenna arrays -- Design
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Sinnamon, Gerald F., "An experimental study of the effect upon the current distribution and radiation pattern of crossbars on Yagi receiving antennas" (1952). Masters Theses. 2615.