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can I make this 20 meter antenna work on 30 also?
All,
I'm finally putting together a vertical antenna that I hope will work on 20 meters. Soil is sandstone with occasional bits of granite, impossible to drill into, it has to be chiseled out with a hand pickaxe. I won't begin to tell you the agony involved in chipping out a 2 1/2 foot cubic hole into this stuff, but I managed to do it. But in any case forget about soil conductivity, and forget about ground rods! There is a single ground rod courtesy of the electrical company... probably not at good depth for RF but it is the only game in town. Construction: The ground half of the antenna starts with 5 foot of 1 inch diameter iron pipe, sunk halfway into hole filled with concrete. 2 1/2 half feet of iron pipe are exposed above the dirt. This is connected to 10 foot of 3/4 inch copper pipe. At the 12 foot level I am mounting 4 radials, 8 foot 1 1/2 inches in length, of 1/2 inch diameter copper pipe. I am also mounting 4 copper guy wires, same length, that are intended to also work as additional radials. The radiative half of the antenna starts with 10 foot of 3/4 copper pipe, topped with a 9 foot carbon fiber fishing pole. A thin copper wire of about 6 foot 3 inches in length will be run up the fishing pole, for a total length of 16 foot 3 inches. I will be mounting rope guy wires on the botttom of the radiative half. The ground half and radiative half are connected together with a PVC coupler, and make contact with each other inside the coupler via a thick styrofoam spacer. Question: This antenna is designed to hopefully work on 20 meters. If I run a wire of 14 feet 4 1/2 inches up the fishing pole instead of the 6 foot 3 inches, and if I use guy wires of 12 foot 2 1/4 inches, leaving the radial lengths unchanged: will I get a vertical that I can work on both 30 and 20 meters? Thanks in advance, The Eternal Squire |
#2
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can I make this 20 meter antenna work on 30 also?
Here is one little trick I tried a couple of years ago, when I had an
elevated 20 meter vertical with the feed point about 10 feet in the air with 4 16 ft radials. I fed it at the base with a 4 to 1 balun, mounted in reverse. I then ran 450 ohm twin lead to the shack with a Johnson Matchbox to tune the feeders..it worked 40 thru 10 meters (some loss on 40 but it did work there ok). If you try this..you need to do something to keep the twin lead from swinging in the wind..or the impendence will change quite a bit. wrote in message oups.com... All, I'm finally putting together a vertical antenna that I hope will work on 20 meters. Soil is sandstone with occasional bits of granite, impossible to drill into, it has to be chiseled out with a hand pickaxe. I won't begin to tell you the agony involved in chipping out a 2 1/2 foot cubic hole into this stuff, but I managed to do it. But in any case forget about soil conductivity, and forget about ground rods! There is a single ground rod courtesy of the electrical company... probably not at good depth for RF but it is the only game in town. Construction: The ground half of the antenna starts with 5 foot of 1 inch diameter iron pipe, sunk halfway into hole filled with concrete. 2 1/2 half feet of iron pipe are exposed above the dirt. This is connected to 10 foot of 3/4 inch copper pipe. At the 12 foot level I am mounting 4 radials, 8 foot 1 1/2 inches in length, of 1/2 inch diameter copper pipe. I am also mounting 4 copper guy wires, same length, that are intended to also work as additional radials. The radiative half of the antenna starts with 10 foot of 3/4 copper pipe, topped with a 9 foot carbon fiber fishing pole. A thin copper wire of about 6 foot 3 inches in length will be run up the fishing pole, for a total length of 16 foot 3 inches. I will be mounting rope guy wires on the botttom of the radiative half. The ground half and radiative half are connected together with a PVC coupler, and make contact with each other inside the coupler via a thick styrofoam spacer. Question: This antenna is designed to hopefully work on 20 meters. If I run a wire of 14 feet 4 1/2 inches up the fishing pole instead of the 6 foot 3 inches, and if I use guy wires of 12 foot 2 1/4 inches, leaving the radial lengths unchanged: will I get a vertical that I can work on both 30 and 20 meters? Thanks in advance, The Eternal Squire |
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