does wire really matter

[wenzeslaus]

people say you need certain thickness or types of wire for your antenna. or thicker wire has more Q factor. or thicker wire doesn't matter because of skin effect. or copper wire conducts electricity better. people need 14 gauge wire to make large loop antennas. on and on.

this guy did a test with 10 different types of wire, including barbed wire, winch cable, clothesline wire, etc. and it didn't make an appreciable difference.

you tell me. does it matter what wire you use?

what I'm concerned with is receiving antennas. random wire and AM loop antennas. does wire also matter (or not) in those?

 

[jwt873]

I've constructed antennas over the years with both stranded and solid conductors from 12 to 14 gauge. I never saw any meaningful difference between the stranded or solid wire.

I find the solid conductor easiest to work with (resists kinking). Right now I have a ~124 foot 80 meter inverted Vee and a Wellbrook antenna with a 30 foot square loop using. Both using 14 gauge solid.. They both work fine.

(I had a bunch of 14 gauge 3 conductor house wiring lying around. I split the outer sheath and used the internal wires).

 

[WA8ZTZ]

Not really for your purposes... whatever you have laying around will probably work fine.
My wire antennas are either 14 or 12 AWG THHN solid copper or 18 AWG Poly Stealth.
All have held up well for many years of ice and wind. The UV will eventually breakdown the nylon
outer jacket on the THHN insulation, not a big deal. They are supported by black Dacron, marine grade
white nylon, or poly line. The Dacron and nylon hold up better than the poly. The poly doesn't like the UV
and is harder to tie a knot. For receiving, if the antenna or the connections get corroded, noise or mixing
products can be introduced.

 

[Boombox]

When I had outdoor antennas I used standard copper stranded wire you could get at Radio Shack. It was heavy duty enough to last, until a tree brought the antenna down. I still have the wire. Some day I might re-erect the antenna.

For MW loop antennas, any wire will do. The size of the wire itself really doesn't matter. The length of wire used to wind the loop matters, and the spacing between windings will affect the performance of the anternna somewhat, but the size of the actual wire doesn't make much difference. I have a box crate loop with stranded, reasonably heavy duty wire and it works as well as a Select-A-Tenna, and I also have a 3.5 ft spiral loop I made with old enamel wire torn from an old CRT TV tube's deflector (?) windings. It still works fine.

 

[cistercian]

For dipoles as long as the wire does not readily corrode and is strong enough to stay up...sure.
For loop antennas of high Q there is a reason Litz wire exists.
As far as wire size in box loops goes bigger is better. Here is a measurement I made on my 4 foot per side box loop with
3 different wire sizes. Remember Q is directly proportional to the voltage developed on the loop as well as the bandwidth.
A crazy high Q loop can be so sharp that you can choose what sideband of an AM signal you want to emphasize! I can't afford
Litz wire and it is also somewhat fragile so I just use magnet wire.

My LC meter only goes to 100kc. 7 turn 4 foot per side box loop. covers the entire AM BCB with my large variable tuning caps.
Measurements made at 100kc.

#22 wire 188mh resistance 1.73 ohms Q 50
#20 wire 186mh resistance 1.07 ohms Q 70
#15 wire 169mh resistance .34 ohms Q 95

This means that the #15 wire produces nearly double the voltage of the #22 wire antenna. I used to use #24 wire because I had
a lot of it. But it was fragile compared to the larger sizes and did not work as well. For many people size of the wire does not matter
if they are not trying for maximum performance. But if you want to maximize your loop antennas performance, bigger in size of the loop first...
then bigger wire.

 

[wenzeslaus]

if Litz wire has better Q, why didn't you use Litz wire instead of #15 wire?

the resistance shouldn't matter due to the skin effect at high freq, therefore

a) you couldn't accurately determine the Q factor

b) that would be an explanation (if true) why any material should work, such as CCA, barbed wire, winch cable, stranded vs solid, etc

the L you measured doesn't say much because you aren't taking into account the spacing between turns. that changes L.

what matters is how it performs. DOES the loop with #15 wire perform better than the others?

 

[Dirk_SDR]

If you look at antennas for lower frequencies (VLF and lower), I wouldn't say that wire (length or turns on a coil) really matters, but copper (or other metal) matters. The more & heavier the better ... 😉

 

[cistercian]

if Litz wire has better Q, why didn't you use Litz wire instead of #15 wire?

the resistance shouldn't matter due to the skin effect at high freq, therefore

a) you couldn't accurately determine the Q factor

b) that would be an explanation (if true) why any material should work, such as CCA, barbed wire, winch cable, stranded vs solid, etc

the L you measured doesn't say much because you aren't taking into account the spacing between turns. that changes L.

what matters is how it performs. DOES the loop with #15 wire perform better than the others?

It is about 2 dollars a foot in the larger sizes. 112 feet of wire on my loop...224 dollars worth. Nope.
More economical thinner Litz wire is also expensive and fragile. That's why I don't use it. The cat sometimes appears
and fools with the antenna. She is no threat to #15 magnet wire!

 

[cistercian]

Wire spacing the same on all wire sizes. I measured it with an LC meter that shows Q. Tested @ 100Kc.
The #15 coil tunes sharper than the other sizes and produces a stronger signal too.
I use the 4 foot loop as a passive AM BCB booster for portables as well as for stand alone crystal set use.
It works much better with #15 than the smaller wire for crystal set use. The difference is large.

The PVC frame is notched for each turn so swapping wire out and measuring was easy. Skin effect is why the larger diameter
wire works better. Lower RF resistance.

 

[wenzeslaus]

so I went to the park and tested two 100 ft wires side by side. (on the ground) 14 vs 24 ga. both were untwisted CCA crap. on shortwave, both had the same volume (about 1.5-2x the telescopic antenna alone) but the 24 ga had a lower noise floor, was noticeably clearer, and voice sounded more articulated. I'm sure there is a technical explanation such as bandwidth or Q factor that I need to figure out- but the point is, there was a difference. neither were terribly better than the antenna but good enough to necessitate their use when digging for faint stations. and the thinner wire was noticeably better.

anybody got a technical explanation?