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Author Topic: copper tubing vs. solid copper wire  (Read 599 times)
FOXBAT426
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« on: August 26, 2007, 12:00:05 PM »

hi, i'm building a vertical and was wondering if 1/2" copper tubing would radiate better than the same length of solid copper wire such as 14 or 12 gauge romex - or does it make a diffrence? tia, john
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N3OX
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« Reply #1 on: August 26, 2007, 12:34:27 PM »

No difference.

The only practical difference you'll see in almost any antenna when you switch to fatter conductors is increased bandwidth.

The resistive loss of #12 wire is pretty much totally insignificant in almost any antenna design.

There are a few designs (magnetic loop antennas, for one) where the current is extremely high at a given power level compared to other antennas and any resistance really makes a difference... even the quarter of an ohm RF resistance of 12 feet of #12 wire would cause about 4dB of loss in a #12 magnetic loop vs. a 3/4" copper tubing antenna.

73,
Dan
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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
W5RKL
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« Reply #2 on: August 26, 2007, 12:44:52 PM »


The antenna impedence is affected by the type and diameter of the conductor used to construct an antenna. Therefore, the antennas impedence will affect the antannas "ability" to radiate. An antenna that has an impedence mismatch will have an affect on its ability to radiate the signal effectively.

Is one better than the other? No, providing all the other factors are taken into consideration.

73's
Mike W5RKL
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NA0AA
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« Reply #3 on: August 26, 2007, 03:38:08 PM »

The only reason for copper tubing in an antenna is for mechanical reasons [like the copper pipe j-pole].  In general, a fatter conductor improves overall bandwidth, but not so much so as to make it a huge difference for most users.

If you want more on that, see the antenna books where they talk about cage type antennas for HF.

Now in a tank circuit, it's a different story.
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N3OX
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« Reply #4 on: August 26, 2007, 04:26:15 PM »

"The only reason for copper tubing in an antenna is for mechanical reasons [like the copper pipe j-pole]."

With the cost of copper the way it is though, it's probably good to start thinking aluminum for most applications....

This is especially true on HF... no copper tubing antenna has any advantage over aluminum, mechanical or otherwise, except magloops ;-)

73,
Dan
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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
ONAIR
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« Reply #5 on: August 26, 2007, 09:47:44 PM »

    You can expect to see copper prices droping on the retail level.  The demand for copper has been falling due to the slumping building industry.
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NA0AA
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« Reply #6 on: August 26, 2007, 10:21:11 PM »

The other reason is that you can build a copper J-pole with just a torch....<G>.  I'm not very good with soldier on Aluminum yet.
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WA3SKN
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« Reply #7 on: August 27, 2007, 04:59:47 AM »

You didn't mention frequency.
But, there is no measurable difference, so use what-ever is most practical for you antenna design!
Cost could be a bigger factor!

-Mike.
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WA9SVD
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« Reply #8 on: August 27, 2007, 07:11:17 AM »

 W5RKL on August 26, 2007    Mail this to a friend!
The antenna impedence is affected by the type and diameter of the conductor used to construct an antenna. Therefore, the antennas impedence will affect the antannas "ability" to radiate. An antenna that has an impedence mismatch will have an affect on its ability to radiate the signal effectively.

Is one better than the other? No, providing all the other factors are taken into consideration.

73's
Mike W5RKL
==========

    And just HOW does the diameter of a radiator affect impedance?  Please explain/elaborate...
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NZ5N
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« Reply #9 on: August 27, 2007, 08:54:12 AM »

At least at VHF, a change in the diameter of the elements affects the resonant frequency.  I have wire verticals for HF and they work fine.
73,
Bill NZ5N
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WA3SKN
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« Reply #10 on: August 27, 2007, 09:04:08 AM »

The impedance will change, but the antenna's ability to radiate WILL NOT!

-Mike.
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