[Antennaware] Help! Which One
kg7hf at comcast.net
Tue Sep 22 14:58:55 PDT 2009
I have to agree fully with Larry's (k0is) comments. It really depends on what you want to do. Height and the amount of ground radials play a major role.
I currently have an 1100 foot horizontal loop at 75 feet. I feed it with homemade 600 ohm ladder line, each spreader is 5 feet apart and made from pvc pipe I split into little thin strips. I run the ladder line right down to the window of the shack where I do directly to a coax balun to the tuner. I earned DXCC with this antenna in the solar cycle minimum using only 100 watts or less.
On the other hand, during a "dxpedition" to Vermont, I used an extended double zepp for 20 meters, about 48 feet each side) fed with radio shack 300 ohm twin lead and worked over 100 countries in a week using the FT-817 qrp rig.
My other antennas include a 20 meter extended double zepp, and a 40 meter extended double zepp both are at 65 feet and fed with 600 ohm home brew feed line. They work very well but only have about a 40 degree beam width. I have anything but anecdotal information, but I get consistent "real" 59 reports running qrp.
I also have a 65 foot vertical made from 3/4 inch copper water pipe at ground level. It has no radials, only a ground rod, and it well...sucks, I hardly ever use it unless I don't want to make a contact. I do think though that if I invested the time into putting a number of radials down, the vertical would begin to work better. I highly doubt though that it will ever outperform the zepp antennas.
Paul's antenna theory is that you want to get as much power transferred to the antenna system as possible. If you are using a tuner to match more than say 5 to 1, then coax is not the way to go.
As far as dipoles, these are great antennas, and with a few traps, you should be able to make a multi-band dipole work fine and feed it without much trouble with coax. Again, height is the key factor for the dipole.
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