Topband: Folded Marconi Antenna
k7rx at comcast.net
Sat Jul 23 17:45:41 EDT 2005
I recently took down my Alpha Delta DX-A twin sloper and want to put up something different. I am not quite ready to shunt feed my tower yet so am looking at ideas for some sort of inverted L system. In the distant past, I ran folded Marconi antennas at different times as a novice on 80 and later on top band. When I made these for top band I would begin with about 130 feet of heavy duty twin lead. At the bottom of the vertical section I would feed one side with coax center and the other with the braid and radials or counter poises. I would then go out an electrical quarter wave calculated for the particular type of line I was using and would tie the two sides together. I would then tie the far end together so that the short section of twin lead tied together at either end acted as a voltage cap.
I have tried to find descriptions of this antenna on the internet without much success. I find the antenna but they don't mention where to tie the ends together and one description actually says that if you put it up as an inverted L, you actually need to make it shorter but it doesn't give any idea of how much shorter it ought to be. I am blind so really can't access Low Band DXing or the ARRL Antenna Book very well so wonder if anyone on the list can tell me if this antenna is in either of them? I would also wonder about the possibility of using 450 ohm window line as opposed to twin lead?
Finally, if any of you have built this antenna or something similar, I would love to see if I am remembering the facts of its construction. In particular, I wonder if you are using a ground rod for mounting the base, would you tie the braid of the coax to one side of the twin lead/window line, the rod and the radial system or would you leave the ground rod out of that part of the circuit? I will welcome any feedback anyone may wish to offer.
Thanks very much all and very 73.
Amateur Radio: K7RX
Navy Marine Corps MARS: NNN0SHS
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