[TowerTalk] Shunt Feed Up Center of Power

[Dennis W0JX]

Shunt feeding of a broadcast tower by running a cable up the center is not a new concept. KOBO in Yuba City CA did this in the early 90's. It is done primarily to allow other services to mount antennas on the side of a tower, thereby increasing rental income.
There was a paper written about this, and other antenna ideas, by Clarence Beverage. It was published in the NAB 1995 Broadcast Engineering Conference Proceedings.
I think the reason that this method is not widely used is that it is difficult to find and adjust the proper tap point by running a cable up the center of the tower. It is much easier to run one up the side and tap different points on the tower until you find that major spot that gives you a 50 ohm match.  My shunt feed works so well that I have not wanted to mess with it and try the center feed method.
If anyone wants a copy of the NAB paper, I can send you the PDF.  However, there is no specific technical info in the article to help you determine a starting point for setting the proper tap point.
73 Dennis W0JXMilan, OH