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#1
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Ed wrote:
What characteristics would a 1/2 wave dipole have if one side was near vertical, and the other side buried along the ground? Would it act like a poorly counterpoised groundplane vertical, or something else? Any redeeming qualities? When two radials are 180 degrees apart and elevated, they tend to cancel the radiation from each other. When you bury one radial, you ensure that ~half your RF energy is lost. If you bury that one radial vertically, you do indeed lose half your signal since you have put half of your dipole underground. Ground mounted verticals give up approximately half their power to ground losses. Then they give up approximately another 3 dB to a rotatable dipole. Approximately 10 ohms of the feedpoint impedance for mobile antennas is ground losses. (Please note that everything I said is approximate. :-) -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
#2
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![]() "Cecil Moore" wrote Ed wrote: What characteristics would a 1/2 wave dipole have if one side was near vertical, and the other side buried along the ground? Would it act like a poorly counterpoised groundplane vertical, or something else? Any redeeming qualities? When two radials are 180 degrees apart and elevated, they tend to cancel the radiation from each other. When you bury one radial, you ensure that ~half your RF energy is lost. If you bury that one radial vertically, you do indeed lose half your signal since you have put half of your dipole underground. Ground mounted verticals give up approximately half their power to ground losses. Then they give up approximately another 3 dB to a rotatable dipole. Approximately 10 ohms of the feedpoint impedance for mobile antennas is ground losses. (Please note that everything I said is approximate. :-) -- 73, Cecil http://www.qsl.net/w5dxp Hello Cecil, Is it appropriate to apply the above discussion to two random-wires, end-fed (coax) from a 4:1 Balun were one half of the Balun output is directly connected to ground? I would like to experiment using one or more radials (laid on the surface of ground at first, buried if that helps). for this antenna. Electrically, the antenna is about 1/8 wavelength for some frequencies, and as much as 9/5 wavelength for others. The angle of the wires is about 45 degrees elevation. One wire is about 76' and the other 42'long. I use an ATU for this antenna and it has no trouble loading anything, however only 5-15 mhz is reliable for DX. Due to the antenna's location on the property line, I could only apply radials 180 degrees (along its axis) and of course if permanent, would have their ends bonded to the station/service ground, etc. Thanks for suggestions... Jack Painter Virginia Beach, Virginia |
#3
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Jack Painter wrote:
Is it appropriate to apply the above discussion to two random-wires, end-fed (coax) from a 4:1 Balun were one half of the Balun output is directly connected to ground? I'm sorry Jack, I don't understand the question. If the two wires are equal length and the currents are flowing in opposite physical directions, the far fields will tend to cancel. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
#4
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![]() "Cecil Moore" wrote in message ... Jack Painter wrote: Is it appropriate to apply the above discussion to two random-wires, end-fed (coax) from a 4:1 Balun were one half of the Balun output is directly connected to ground? I'm sorry Jack, I don't understand the question. If the two wires are equal length and the currents are flowing in opposite physical directions, the far fields will tend to cancel. -- 73, Cecil http://www.qsl.net/w5dxp Sorry Cecil, I'll be more clear: I have a random wire antenna, it has one coax-attachment (feedpoint) from which two different length wires start from a 4:1 Balun on a ground rod, up to a Pine tree about 60' in the air. The shorter 42' wire terminates via insulated connector and non-conductive line to the main 76' wire that continues skyward (about a 45 degree angle) until it terminates at an insulator before the support line finally connects it to the high tree limb. Some folks call this a "fan" arrangement. A Radio Works 4:1 current-type Balun has two output connectors, and both random wires start at one of those connectors. The other connector (normally intended for the other half of a dipole) is shorted to the ground rod the Balun is mounted to. This is a noise-limiting design from an old Fine Tuning "Proceedings" article. My question is, if I added a long radial (on the ground) from that ground rod, all the way under the sloping antenna wires, would there be any benefit in the transmitting pattern? How about two radials, 180 degrees from each other (one under the antenna, the other 180 degrees away from it)? I sounds kind of like creating an 1/2 underground dipole, which you and others well explained is a non-starter. But the antenna also has characteristics similar to an inverted-L, and I believe those can benefit from radials. The antenna has been easy to manually tune via an MFJ-962D, and an MFJ-994 ATU makes quick work of any thing I have loaded it with. Could radials improve this "random wire(s)" antenna, or just soak up more power? Thanks a lot, Jack |
#5
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Jack Painter wrote:
My question is, if I added a long radial (on the ground) from that ground rod, all the way under the sloping antenna wires, would there be any benefit in the transmitting pattern? How about two radials, 180 degrees from each other (one under the antenna, the other 180 degrees away from it)? If I understand it correctly, I would guess that radials would help that antenna. Sounds like you are losing half your power in the ground rod. Two radials are better than one and the more radials the better. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
#6
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![]() "Cecil Moore" wrote Jack Painter wrote: My question is, if I added a long radial (on the ground) from that ground rod, all the way under the sloping antenna wires, would there be any benefit in the transmitting pattern? How about two radials, 180 degrees from each other (one under the antenna, the other 180 degrees away from it)? If I understand it correctly, I would guess that radials would help that antenna. Sounds like you are losing half your power in the ground rod. Two radials are better than one and the more radials the better. -- 73, Cecil http://www.qsl.net/w5dxp Thanks Cecil. It probably is a power-sink when xmit. The antenna was originally set up as a receive-only antenna, and you should hear the difference in volume when the grounded side of the Balun is off/on the ground rod. Audible increase (for DX purposes, where a couple of S-units is a lot, hi). I'll try the radials, and disconnect the shorting ground, and see if this improves things a little. I never heard anyone mention making a "vee" dipole antenna (from the ground-up), is that a NVIS? Jack |
#7
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Jack Painter wrote:
I never heard anyone mention making a "vee" dipole antenna (from the ground-up), is that a NVIS? A balanced-V would not have very much vertically polarized radiation and thus would probably be an NVIS. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
#8
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On Tue, 1 Feb 2005 11:41:50 -0500, "Jack Painter"
wrote: Thanks Cecil. It probably is a power-sink when xmit. The antenna was originally set up as a receive-only antenna, and you should hear the difference in volume when the grounded side of the Balun is off/on the ground rod. Audible increase (for DX purposes, where a couple of S-units is a lot, hi). I'll try the radials, and disconnect the shorting ground, and see if this improves things a little. I never heard anyone mention making a "vee" dipole antenna (from the ground-up), is that a NVIS? Jack I would think it would be NVIS. A lazy Vee ( horizontal wires) is directional going from the point through the midpoint between the two ends. If it is directional horizontal, it must be directional pointed strait up. -- 73 for now Buck N4PGW |
#9
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On Tue, 1 Feb 2005 01:02:21 -0500, "Jack Painter"
wrote: "Cecil Moore" wrote in message ... Jack Painter wrote: Is it appropriate to apply the above discussion to two random-wires, end-fed (coax) from a 4:1 Balun were one half of the Balun output is directly connected to ground? I'm sorry Jack, I don't understand the question. If the two wires are equal length and the currents are flowing in opposite physical directions, the far fields will tend to cancel. -- 73, Cecil http://www.qsl.net/w5dxp Sorry Cecil, I'll be more clear: I have a random wire antenna, it has one coax-attachment (feedpoint) from which two different length wires start from a 4:1 Balun on a ground rod, up to a Pine tree about 60' in the air. The shorter 42' wire terminates via insulated connector and non-conductive line to the main 76' wire that continues skyward (about a 45 degree angle) until it terminates at an insulator before the support line finally connects it to the high tree limb. Some folks call this a "fan" arrangement. A Radio Works 4:1 current-type Balun has two output connectors, and both random wires start at one of those connectors. The other connector (normally intended for the other half of a dipole) is shorted to the ground rod the Balun is mounted to. This is a noise-limiting design from an old Fine Tuning "Proceedings" article. My question is, if I added a long radial (on the ground) from that ground rod, all the way under the sloping antenna wires, would there be any benefit in the transmitting pattern? How about two radials, 180 degrees from each other (one under the antenna, the other 180 degrees away from it)? I sounds kind of like creating an 1/2 underground dipole, which you and others well explained is a non-starter. But the antenna also has characteristics similar to an inverted-L, and I believe those can benefit from radials. The antenna has been easy to manually tune via an MFJ-962D, and an MFJ-994 ATU makes quick work of any thing I have loaded it with. Could radials improve this "random wire(s)" antenna, or just soak up more power? Thanks a lot, Jack Sounds an awful lot like a form of J-Pole antenna. -- 73 for now Buck N4PGW |
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