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Alsworld
| | Posted on Sunday, November 02, 2003 - 9:33 pm: | 
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Okay, here is the deal. Not that I want to look like the biggest idiot on the Copper Electronics Forum, but I started to think out of the box and figured I'd put it to the forum for some answers.
I just made a dipole antenna last night. Got it up today after the Net unfortunatly, but tuned it to low SWR's, used 6 turns of coax as a simple balun and it seems to work okay. With the IMAX 2000 being vertical, I have the dipole horizontal. Will try it out next Sunday unless I can get a radio check sooner on it.
Anyways I got to thinking (which can be scary), with a dipole, the larger the wire, typically the more broadbanded it is. Fairly generic statement I admit, but it started churning up questions in my head.
1) Why does no one try and build a 5/8ths wave dipole?
2) Could a dipole be made out of copper tubing vs copper wire? Works great for J Pole antennas.
3) Being Copper conducts electricity better than aluminum, would a copper yagi have any noticable difference over an aluminum yagi?
Yes I fully understand corrosion and how it affects both metals, and the copper antenna would have to be cleaned on a regular basis to maintain proper conductivity.
Yes Copper is heavier (and softer), more windload and weaker with an ice load.
Yes copper is more expensive (but more readily available where I am)
Thoughts anyone?
Alsworld |
Ca346
| | Posted on Monday, November 03, 2003 - 12:36 pm: |
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My G5RV was set up (past tense) with a East/West orientation for one leg and a SE/NW orientation for the other leg. It was VERY directional. Center was at 36ft with each end sloping down to 20ft. From central California, I was getting Alask and Washington State on one leg, and all the way accross the US with the other leg.
My point is this: What orientation did you set it up at? I think it will make a VERY big difference. And sloping it also makes a BIG difference. |
Highlander
| | Posted on Monday, November 03, 2003 - 5:18 pm: |
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Well, I know the answer to question 2 is yes. The answer to 3 is probably not noticeable on the air, and it would be heavier for sure. |
Alsworld
| | Posted on Tuesday, November 04, 2003 - 12:06 am: |
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Ca346,
I put this dipole in a east/west direction. To my west is nothing but ocean. With Tech808 having his beams, I will try and see how it affects his receive once contact is established on the ground plane. About a thousand miles between us but it will be interesting to see if contact can be maintained with it.
Alsworld |
Ca346
| | Posted on Tuesday, November 04, 2003 - 11:13 am: |
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ALS:
Once in a very great while I get some QSO's with people here in the Western U.S. But, not very often. I have connected with Seatle, WA once or twice, but I don't remember what antenna system he was using. I have pointed my beam due North more than once to see if I can hear anybody in Northern California, Oregon, or Washington, but it is pretty quiet. Radio skip is a strange animal! |
Stickshift
| | Posted on Tuesday, November 04, 2003 - 12:11 pm: |
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Alsworld,
The following text is taken directly from "Now You're Talking!", published by The American Radio Relay League:
"Dipole antennas send radio energy best in a direction that is 90o to the antenna wire. For example, suppose you install a dipole antenna so the ends of the wire run in an east/west direction. This antenna would send stronger signals in north and south directions."
I have a half-wave dipole that I constructed from old lamp-cord and a short piece of RG-58/U. I had that thing hanging from the beams in the attic of my parents house for years. It was inverted running east to west. I talked 45 miles north with a stock Uniden Washignton. Granted, it wasn't a strong signal, but it just prooves that it doesn't take much to build a simple dipole.
I have that exact dipole strung up in my home here. It is inverted at 45o running east to west. I have the swr tunned to 1:1.1 on 27.115 Mhz. This thing is fairly broad-banded, with hardly no change through the entire 40 channel CB spectrum. The antenna is, again, inside my home, (not as good as outside, and probably not all that good for your health). I have talked to the same town 45 miles north and another 40 miles south. I mainly use it for recieving with another radio, but it will definetly transmit.
Hope this helps
73's
stickshift |
Alsworld
| | Posted on Tuesday, November 04, 2003 - 9:44 pm: |
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Stickshift,
yes you are correct and I misstated in my post. The wire is actually running due north and south, to give me the east/west directional properties. I was thinking east/west direction patterns, but sure didn't say that ha ha ha .
With only ocean to my west, little noise, hence me trying to catch 808 on his beams (we have had great luck with me on only the IMAX 2000). I am trying the horizontal polorization and see if it makes a significant difference.
Okay, actually I know that it would, but Tech808 runs a quad so he will receive me fine on the IMAX, but I would like to see how my dipole will get through when conditions are running. This is based on the past two weekends where we never had a problem talking to each other.
Also, if another agitator comes in, will one outperform another? I'm reaching for the dipole to beat out the 5/8ths wave IMAX, but that is where polorization may come into play. I may be reaching there as well but the horizontal dipole can sometimes be quieter but still bring in the voices. I have not radio checked it yet.
Aw shoot (shaking my head), hold up. I am not comparing one to the other, I just want to see if my dipole works. This sentence beats trying to edit the above. Maybe that sound better.
Either way, it was a fun project and I'll keep it for awhile and eventually get it higher (about 16 ft off, and parallel to the ground now).
Good input for sure! Thanks Stickshift.
Oh and by the way for all who read this, question #3 above was my thinking of building a small copper tube dipole I could mount to be rotatable, giving it direction to wherever I "pointed" it. Then I thought of adding a reflector, and maybe director which in turn turned out to be 'what I called' a yagi. Wrong terminology. I pictured a flat beam like the Maco flatsides (NOT a Yagi).
I just got carried away from building a simple dipole and started grunting like Tim Allen. I like working with copper, and have a great spot for a "hard" dipole that I could rig to rotate, and a reflector would be great. But....I'm planning on building a Quad anyway so bottom line, it was a useless question. A copper yagi....go figure!
Alsworld |
Mr_Rf
| | Posted on Tuesday, November 04, 2003 - 10:14 pm: |
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1. You have the right idea...
2. Copper would work ok
3. No real gain between copper vs aluminum
This is a general idea of how to add sections to asimple dipole creating gain:
Additional stubs and 1/2 wave sections may be added but it takes double the number of 1/2 wave sections that you already have each time you increase the length to see a 3dB increase in gain.
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Alsworld
| | Posted on Wednesday, November 05, 2003 - 10:14 pm: |
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Now that is interesting! thanks Mr Rf.
I will shutup now as I think what I described might have been a yagi afterall. I was typing things from memory instead of checking simple facts on a previous statement. Foot is now inserted deeply on something far too basic.
Shame on me.
I'm back out and studying.
Alsworld |
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