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1-10 of 24 messages
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Multi band vertical vs home brew wire antennas
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by M1DYS on November 8, 2006
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I have a large (40ftX 45ft) garden surrounded by tall trees. These would appear to be a Godsend for hanging wires from, but alas they seem to get in the way of each other. I've spent a lot of time staring into the air trying to work out the best configurations I could have for home brew wire antennas. So far they are:
1) A wire 40ft vertical earthed with a spike
2) An end fed horizontal
3) An inverted L
4) A 1/4 dipole for 40 meters center fed.
5) A half square
Now I could have all of these & switch between them, but my question is, given the amount of tree climbing & hassle involved in getting these in the air would I not be better served in terms of performance & convenience, better off buying an 'off the shelf' vertical?
I understand there are some gains & directional properties of wires whereas of course the vert is omni-directional. But would the all round gain make up for lack of directionality?
Many thanks in advance for any advice.
Robert
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RE: Multi band vertical vs home brew wire antennas
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by WB2WIK on November 8, 2006
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>Multi band vertical vs home brew wire antennas Reply
by M1DYS on November 8, 2006 Mail this to a friend!
I have a large (40ftX 45ft) garden surrounded by tall trees. These would appear to be a Godsend for hanging wires from, but alas they seem to get in the way of each other. I've spent a lot of time staring into the air trying to work out the best configurations I could have for home brew wire antennas. So far they are:<
::Let's look at each.
1) A wire 40ft vertical earthed with a spike
::Earthed with a "spike" is the same as no ground at all, when it comes to RF. The only frequency where this is likely to work worth a darn is where the vertical is 1/2-wavelength (or 1 full wavelength), where it is voltage-fed rather than current-fed, so the ground losses won't be so terrible. 40' is 1/2-wavelength at 11.7 MHz, so that's not a very useful length. If you made the length 33 feet instead, you'd have a 1/2-wave vertical for 20m that's a 1-WL vertical for 10m and on both bands, provided you can "match" it by using a tuning network at the base of the antenna (to transform a few thousand Ohms down to 50 Ohms for coaxial feed), it should work pretty well as a "ground independent" vertical. On other bands, it wouldn't work well at all. The thing is, if you want a vertical antenna that can be fed directly with coax and also actually *work*, you need to use radials under it -- lots of them. A "spike" is no replacement for even one radial.
2) An end fed horizontal
::Usually a disaster. End-fed horizontal antennas have no place for RF current return and therefore tend to use the transmission line itself for that function: A bad idea, usually a huge RFI generator and poor performer.
3) An inverted L
::Great idea, but once again, you need to use radials under it -- lots of them. An inverted L is a vertical that happens to be "bent."
4) A 1/4 dipole for 40 meters center fed.
::What's a 1/4 dipole? If you mean a dipole that's only 1/4-wave long, and thus half the length of a real dipole, that doesn't work. However, you can easily install a *real* dipole (1/2-wave, center fed) if you simply install it as a center fed inverted-U, which is a dipole that has its two "ends" hanging down towards earth to compress the horizontal space it occupies. One for 40m will work well on 40m and on 15m, but not on any other bands.
5) A half square
::You could try that, but feeding it can be tricky and if fed at a lower corner, still requires radials.
::With a 40' x 45' garden that has a lot of trees, I'd probably install a ladder-line fed loop antenna using the entire perimeter of the garden (170 feet total) and just tune it using a balanced line tuner in the shack. This should work the absolute best of any non-directional wire antenna you can install, and it will work on 40-30-20-17-15-12-10m pretty well, and should work to some extent on 80m also. Get it up as high above ground as possible, get a good balanced line tuner, and have fun!
WB2WIK/6
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RE: Multi band vertical vs home brew wire antennas
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by KE4VBG on November 8, 2006
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Here's an excellent article on the Loop Skywire. Just make it as long as you can . Like Steve says you won't be disappointed. I sure like mine.
http://srgproperties.inetusanow.net/files_custom/9467_2192.pdf
73, Doug
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RE: Multi band vertical vs home brew wire antennas
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by KE4VBG on November 8, 2006
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Here's an excellent article on the Loop Skywire. Just make it as long as you can . Like Steve says you won't be disappointed. I sure like mine.
http://srgproperties.inetusanow.net/files_custom/9467_2192.pdf
73, Doug
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RE: Multi band vertical vs home brew wire antennas
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by KE4VBG on November 8, 2006
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Here's an excellent article on the Loop Skywire. Just make it as long as you can . Like Steve says you won't be disappointed. I sure like mine.
http://srgproperties.inetusanow.net/files_custom/9467_2192.pdf
73, Doug
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RE: Multi band vertical vs home brew wire antennas
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by KE4VBG on November 8, 2006
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Here's an excellent article on the Loop Skywire. Just make it as long as you can . Like Steve says you won't be disappointed. I sure like mine.
http://srgproperties.inetusanow.net/files_custom/9467_2192.pdf
73, Doug
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RE: Multi band vertical vs home brew wire antennas
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by KE4VBG on November 8, 2006
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Mail this to a friend!
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Here's an excellent article on the Loop Skywire. Just make it as long as you can . Like Steve says you won't be disappointed. I sure like mine.
http://srgproperties.inetusanow.net/files_custom/9467_2192.pdf
73, Doug
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RE: Multi band vertical vs home brew wire antennas
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by KE4VBG on November 8, 2006
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Mail this to a friend!
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Here's an excellent article on the Loop Skywire. Just make it as long as you can . Like Steve says you won't be disappointed. I sure like mine.
http://srgproperties.inetusanow.net/files_custom/9467_2192.pdf
73, Doug
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RE: Multi band vertical vs home brew wire antennas
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by KE4VBG on November 8, 2006
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Mail this to a friend!
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Here's an article on the Loop Skywire. I sure like mine.
http://srgproperties.inetusanow.net/files_custom/9467_2192.pdf
73, Doug
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RE: Multi band vertical vs home brew wire antennas
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by KE4VBG on November 8, 2006
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Sorry Steve, I don't know what happened on that post. Please clean out the Dupes if you want.
Thanks, Doug
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