best or acceptable wire size for dipole

[AI3V]

Here you go Jim!

http://en.wikipedia.org/wiki/Skin_effect

http://en.wikipedia.org/wiki/Litz_wire

I have seen a lot of 60cy transformers wound with square wire, My experence is with small- less than 1kva- transformers. The wire cross section is much smaller than the skin depth, and I believe the square is used so you can fit more Cu in than if the wire was round.(less copper loss).

As far as designing a xformer for wide bandwidth, I havn't a clue, Maybe Gnomes?

Rege

[AG3Y]

Ron, I have heard of people using fence wire, stainless steel wire, regular house wiring wire and aluminum wire, stranded, solid, copper clad, insulated, bare, etc. etc.

We may be discussing skin effect, cross sectional conductance, etc. here, but in reality, most wire radiates about as good as any other kind, at least from a ham's perspective.

Aluminum wire has two faults, you cannot solder to it, at least not easily, and it does have a tendency to get brittle and break, usually at the most inopportune times ( like during a contest ! )

But if you like experimenting with wire antennas, are probably not going to keep a particular antenna up in the air for a long time, and want to use something far less expensive than the going rate for copper, aluminum wire might do the job for you!

As someone pointed out in another post, aluminum is used for all kinds of beam antennas, and they have been known to work well for YEARS! Of course we are talking about tubular material, rather than solid, but there is something good to be said for the stuff!

73, Jim

[WB2WIK]

r

"The skin depth is inversely proportional to the square root of the conductivity of the material. ..."

::Wait a minute. Inversely proportional to the square root would mean that as conductivity improves, skin depth is deeper; as conductivity worsens, skin depth is shallower. Inverse proportion means that as the absolute value or magnitude of one variable gets bigger, the absolute value or magnitude of another gets smaller, such that their product (the constant of proportionality) is always the same.

My original question related to WD5ABC's comment that skin depth becomes deeper for less conductive wire. Based on your quotation above, that wouldn't be true, so the quote agrees with me.

WB2WIK/6

[KL7AJ]

The difference in conductivity for solid vs. stranded copper wire is so small as to be un-measureable, at least by any methods a ham radio operator is likely to have in their possession.

However, solid wire is more likely to become brittle due to flexing in the wind, and more prone to break sooner than equivalent stranded wire would.

There are several types of copper wire available, in many different gauges. If you want to have the wire rather hidden, you obviously would need to go for some smaller stuff such as 16 or 18 gauge. But if you have no problem with that, you will want to go toward 14 or 12 gauge. Remember, the lighter stuff can stretch, twist and break, and the heavier stuff can cause problems just because of its size and weight.

There is a type of wire that is very strong, and still conducts very well. I am referring to copper-clad steel cored wire. However this stuff is quite difficult to work with, as it tends to coil and kink unless you have a means to keep it stretched out as you work with it.

For general all around use, I would probably stick with something like 14 ga stranded wire.

SVD got his post published first. It is good to see that we agree!


Hope this helps! 73, and welcome to the avocation. Jim

JIM!

You bad bad man! Unleashing copperweld on a poor unsuspecting soul like that!
Where is your soul?

Eric

[KL7AJ]

The difference in conductivity for solid vs. stranded copper wire is so small as to be un-measureable, at least by any methods a ham radio operator is likely to have in their possession.

However, solid wire is more likely to become brittle due to flexing in the wind, and more prone to break sooner than equivalent stranded wire would.

There are several types of copper wire available, in many different gauges. If you want to have the wire rather hidden, you obviously would need to go for some smaller stuff such as 16 or 18 gauge. But if you have no problem with that, you will want to go toward 14 or 12 gauge. Remember, the lighter stuff can stretch, twist and break, and the heavier stuff can cause problems just because of its size and weight.

There is a type of wire that is very strong, and still conducts very well. I am referring to copper-clad steel cored wire. However this stuff is quite difficult to work with, as it tends to coil and kink unless you have a means to keep it stretched out as you work with it.

For general all around use, I would probably stick with something like 14 ga stranded wire.

SVD got his post published first. It is good to see that we agree!


Hope this helps! 73, and welcome to the avocation. Jim

JIM!

You bad bad man! Unleashing copperweld on a poor unsuspecting soul like that!
Where is your heart?

Eric

[WB2WIK]

And if this were not true, than nobody would use stainless steel antennas mobile, We would all use some sort of copper alloy!!!!

Rege

::That's not a good conclusion. Mobile whips are very short and even when made from stainless steel still have very low resistance simply because they're short. Big difference between a mobile whip and a 160 meter dipole, which is 260 feet long.

Also, you can improve the performance of a stainless steel whip by plating it with a better conductor, as Larsen has done for four decades now. The Larsen "Kulrod" (cool rod) design, made famous in the early 1970s, is a radiating whip with a stainless steel core which is then copperclad and then silver plated. That's why they don't stay shiny for very long, they get tarnished just like any other silver material. Larsen did this because it actually does improve radiation efficiency at VHF and UHF, so 40 years ago he started making all his whips this way to give him a small edge over the competition. He also brilliantly used large-diameter, edge wound silver plated ribbon inductors as matching coils for the 5/8-wave whips, and those have less loss than the competitors' ordinary coiled wire.

So, now you know!

WB2WIK/6

[VK2AKG]

direct email to Jim:

G'day Jim,

the wikipedia page I linked earlier shows the formula you require.

http://en.wikipedia.org/wiki/Skin_effect

I have attached some scans to this email for your information.

Regards,

Frank vk2akg ZZZzzzz... it's 0146 hrs here


Attachments:
\\192.168.0.173\h\scanner_c3100\std_hbk_1941_pp234-7.pdf
\\192.168.0.173\h\scanner_c3100\skin_effect_harvey 1963.pdf
\\192.168.0.173\h\scanner_c3100\skin_field_and_wav es.pdf

[K9STH]

Actually, the NFPA NEC (National Electrical Code) specifies in 810C Section 810-52 the following:

Minimum Size of Conductors Where Maximum Open Span Length Is

Less than 150 feet: Hard drawn copper 14 gauge. Copper-clad steel, bronze, or other high-strength material 14 gauge.

Over 150 feet: Hard-drawn copper 10 gauge. Copper-clad steel, bronze, or other high-strength material 12 gauge.

Section 810-53. Size of Lead-in Conductors. Lead-in conductors for transmitting stations shall, for various maximum span length, be of a size at least as great as that of conductors for antennas as specified in Section 810-52.

Now that means when using open wire line that the minimum size of each of the wires must be at least 14 gauge when the antenna length is less than 150 feet or, generally since copper-weld is not usually used for feed-lines, 10 gauge for antennas longer than 150 feet. Frankly, how many amateur radio operators actually adhere to this? Not that many! Therefore, the majority of amateur radio operators actually have wire antennas that are fed with open wire line that are, technically, in violation with the NFPA NEC!

As for using galvanized fence wire for antennas, I have found that in a practical sense there just is no difference between this, copper, and aluminum. Antennas like the HyGain HyTower use a galvanized steel tower for most of the antenna and those antennas work great. Also, AM broadcast stations typically use galvanized steel towers for their antenna system and those work great. Now I do not have any wire antennas made from galvanized steel wire "up" right now (although in the past I have used them without any problems). But, all of my elevated radials "under" my HyTower and my full sized 40 meter vertical are made from galvanized steel wire. Those work great as well.

Can the difference between wire types be measured? Certainly! However, it takes some pretty sophisticated test equipment to tell the difference. Therefore, for all practical purposes, it really doesn't matter whether or not you use galvanized steel, copper, or aluminum wire. The same thing goes for the gauge. Yes, the larger the diameter of the wire the more "broad band" the antenna will be and things like a "cage" dipole will have a broader SWR range. But, for most amateur radio applications the "usual" wire gauges ranging from 18 gauge to 10 gauge are going to perform pretty darn well.

Glen, K9STH

[KL7AJ]

Actually, the NFPA NEC (National Electrical Code) specifies in 810C Section 810-52 the following:

Minimum Size of Conductors Where Maximum Open Span Length Is

Less than 150 feet: Hard drawn copper 14 gauge. Copper-clad steel, bronze, or other high-strength material 14 gauge.

Over 150 feet: Hard-drawn copper 10 gauge. Copper-clad steel, bronze, or other high-strength material 12 gauge.

Section 810-53. Size of Lead-in Conductors. Lead-in conductors for transmitting stations shall, for various maximum span length, be of a size at least as great as that of conductors for antennas as specified in Section 810-52.

Now that means when using open wire line that the minimum size of each of the wires must be at least 14 gauge when the antenna length is less than 150 feet or, generally since copper-weld is not usually used for feed-lines, 10 gauge for antennas longer than 150 feet. Frankly, how many amateur radio operators actually adhere to this? Not that many! Therefore, the majority of amateur radio operators actually have wire antennas that are fed with open wire line that are, technically, in violation with the NFPA NEC!

As for using galvanized fence wire for antennas, I have found that in a practical sense there just is no difference between this, copper, and aluminum. Antennas like the HyGain HyTower use a galvanized steel tower for most of the antenna and those antennas work great. Also, AM broadcast stations typically use galvanized steel towers for their antenna system and those work great. Now I do not have any wire antennas made from galvanized steel wire "up" right now (although in the past I have used them without any problems). But, all of my elevated radials "under" my HyTower and my full sized 40 meter vertical are made from galvanized steel wire. Those work great as well.

Can the difference between wire types be measured? Certainly! However, it takes some pretty sophisticated test equipment to tell the difference. Therefore, for all practical purposes, it really doesn't matter whether or not you use galvanized steel, copper, or aluminum wire. The same thing goes for the gauge. Yes, the larger the diameter of the wire the more "broad band" the antenna will be and things like a "cage" dipole will have a broader SWR range. But, for most amateur radio applications the "usual" wire gauges ranging from 18 gauge to 10 gauge are going to perform pretty darn well.

Glen, K9STH

Also keep in mind that A.M. broadcast towers are made of iron....and generally not even galvanized. But WIK's comments about skin effect on SHORT antennas where the current density is very high, is well taken.

The fact of the matter is that rural hams have been using fences for antennas for a century.

Whatever works!

eric

[VK2AKG]

::Wait a minute. Inversely proportional to the square root would mean that as conductivity improves, skin depth is deeper; as conductivity worsens, skin depth is shallower.

Please read the introduction on the wikipedia link provided and play with some numbers on your calculator.

My original question related to WD5ABC's comment that skin depth becomes deeper for less conductive wire. Based on your quotation above, that wouldn't be true, so the quote agrees with me.

WB2WIK/6

I think not.

73 Frank