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Discussion Starter #1
I have an idea how to build light and strong antenna elements.

I will call them Composite Antenna Elements.

Composite in the sense that the antenna element is made of more that one material bonded together in order to get the required and best properties of both materials.

example / idea
[there might be *other* materials or methods to achieve a composite element ... this is just the idea I have for the moment]

Material #1: fibreglass rod or tube: very light, strong, rigid yet flexible, non-conductive. Won't bend. Will hold it's shape. Will flex rather than bend or break under wind or snow/ice or bird load. (approx 1/4 or 3/8 inch dia ? )

Material #2; soft thin aluminum or copper foil strip, long thin rectangular piece, carefully cut and wrapped lengthwise down the length of the rod and bonded to it by a glue or varnish or urethane. Then coated a few times on the outside to seal it in and protect it from moisture, weather or corrosion. Provides the conductivity required for the antenna element while utilizing the least amount of metal necessary to do the job.

Imagine a co-linear GH reflector rod with the gap.

You could cut the full length fibreglass rod or tube for both sides, secure the rod/tube in place on the GH frame, then carefully glue two metal strips to the rod or tube on the outside, one on each side, with the correct gap spacing, and form the conductive metal foil lengthwise round the rod.

When finished the whole antenna, give it a few coats of clear tough urethane.

If necessary you can re-coat the antenna a couple times, if the outer coating is starting to weaken or wear.

I have read that soft (annealed) copper has better conductivity than harder copper. That makes sense, cause if the metal is soft and not under stress, the electrons are more free to move.

And a soft metal is easier to cut and form around the rod or tube.

Finding the right THICKNESS of foil or sheet to use might be important.
Just thick enough to cut and make it workable. But not too thin or it will be too flimsy to work with.

How to cut long thin strips ? Paper shear? Linguini pasta cutter machine?
Simple scissors?

It might be possible to try with simple household aluminum foil ... if one was careful enough.

Just an idea ... but I think this might just work.

Wanted to hear what others thought about this.

Does anyone out there do this already? Any company? Antenna manufacturer?

What'd y'all think ?
 

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Does anyone out there do this already? Any company? Antenna manufacturer?
No company that I know of, but a few people on this forum have built reflectors that way, using aluminum foil on rods.

Material #1: fibreglass rod or tube: very light, strong, rigid yet flexible, non-conductive. Won't bend. Will hold it's shape. Will flex rather than bend or break under wind or snow/ice or bird load. (approx 1/4 or 3/8 inch dia ? )
Thin walled aluminum tubing is lighter than fiberglass rod.
 

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Agreed: Aluminum is lighter than fiberglass.

I've found fiberglass to be an effective material in antenna construction with vertically polarized applications (such as amateur radio). With TV, which is horizontally polarized, the weight of fiberglass is difficult to manage.
 

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Discussion Starter #4
Hmmm ... ok ... maybe solid fibreglass rod is heavier than AL thin tube.

But I might give it a try anyway and see if it is practical to try and actually make this sort of element - by hand at home with available materials. Have to experiment to learn about this ...

Especially for the GH collinear rod reflector elements - with gap - seems to me that this might be an alternate method of construction worth investigating. May simplify construction in some ways - no need for collinear spacer - "unobtanium" pieces. Single continuous rod.

Maybe stay with solid metal wire or rod (AL or CU) for zig zag receive elements.

I'm thinking about only covering half the circumference of the rod ... the front half ... with the foil. The side that faces the incoming signal.

I'm thinking that using a thinner fibreglass rod (say 1/4 inch rather than 3/8) - if I can find 1/4 rod - gives less wind load - and strength. The GH reflector rods are not too long ... so should not sag too much ... if supported only from the middle. Not sure ... Will have to experiment and try.
[ Driveway reflector marker rods? Fibreglass support rod ?]

If building an antenna for indoor or attic use ... could use a rod material other than fibreglass - even wood dowel. Have seen long lengths of wood dowel at the hardware store - many different sizes. (even square wood or trim would work for reflector for indoors I think - if you have trim handy. But round rod is probably best for wind load).

With much less metal required for this sort of element ... I am wondering if more conductive materials could be used. Silver is more conductive that copper (isn't it?). So ...thin silver foil. Or other alloys. Superconductor alloys? (that would be for a high end - high performance type antenna)

Silver corrodes / oxidizes (doesn't it?) - so you'd have to seal it in good ... I think.
Even AL and CU corrode ... but maybe I'm wrong ... Pure Silver does not corrode easily(?)... it's silver coating / plating that goes dark.

Wonder if conductivity makes much of a difference in antenna performance.

Those are my recent thoughts.
 

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If constructing an outdoor antenna, remember to account for ice, wind, snow and bird loading.
 

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Silver is more conductive that copper (isn't it?).
Yes it is.

Wire conductivity

Below a wire conductivity table to be used for LD card type 5, wire loading

Material Conductivity
S/m
Perfect 9.9e99 (lossless)
Silver 6.29e7
Copper 5.80e7
Pure Alumin. 3.77e7
Al. 6063-T832 3.08e7
Al. 6061-T6 2.49e7
Brass 1.56e7
Phospor bronze 9.09e6
Stnlss Stl 302 1.39e6
Wonder if conductivity makes much of a difference in antenna performance.
It does, in various ways and amounts.
 

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Discussion Starter #8
Carbon Fibre as antenna structural parts.

upchuck247 said:
If there are no cost restraints them we could use carbon fibre instead of fibreglass.
Ya (!) Carbon fibre would probably be VERY strong ... probably excellent structurally ... maybe expensive - as you mention. Maybe hard to find.
(High end, professional sports stuff? Archery shafts? Badminton racket shafts? Hockey Stick shafts? Golf club shafts?)

One thing I was wondering .... does carbon fibre material have any sort of signifigant conductivity?

Given it is made with carbon ... and carbon is used for resistors.

Carbon conducts a little ... does it not? And would that amount of conductivity affect antenna performance if used in the antenna support structure.
 

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How does carbon fibre hold up against the sun?
 

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Discussion Starter #10
Not sure how Sunlight / U.V. light affects carbon fibre or fibreglass.

But ...

In other parts of the FORUM, some suggest painting parts that are affected by Sunlight / U.V. light.

So ya ... that was another thought ... Paint the antenna frame with an appropriate paint before applying the metal foil.

Then clear coat everything afterwards with a few coats (varathane? urethane?)

1. Build the entire antenna frame.

2. Paint the entire antenna frame for U.V. protection (appropriate paint?).

3. Attach / glue the metal foils to the painted composite elements.

4. Seal everything together with a few clear coats. (varathane? urethane?)

Certainly these are all important considerations ...

Because ... if you are going to build an antenna yourself with exotic or expensive materials... and put a fair bit of time, labour, effort and money into it... you'd want to protect that antenna, so it will last a long time.
 

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Can you paint carbon fibre? Whenever I've seen it, the colour appears to be embedded into the material, not adhered to like paint.
 

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Discussion Starter #12
Well, hopefully you could paint a part (rod or tube) made of carbon fibre.

I think if you prepare the surface of the part properly, you should be able to add a coat or coats of paint to it.

Not sure ... but I imagine yes.

Maybe a light, very fine sanding first. Primer if required.

Careful if sanding anything with fibres in it ... fibreglass may expose glass fibres. Cabon fibre - maybe the same.

Just need to take the gloss off it ... so the paint sticks ... and make sure it is clean and clear of any oil or greasy substance.

Usual painting drill.
 

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I will call them Composite Antenna Elements.
That sort of thing has been done for many years in Amateur radio. Also, take a look at some marine radio antennas. Even a folded dipole, made from twin lead, might be considered "composite".
 

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re carbon fibre.... its basically the same as fibre glass construction just that carbon fibre is used in place of glass fibre.... the surface that you are painting is the resin that holds the carbon fibre in place.... think formula one race car bodies.... carbon fibre that is painted to the cars paint scheme... or a lot of fast kit planes are now using carbon fibre fuselage parts which are usually painted white with some colour here and there. any carbon fibre part that you see the black carbon weaving is because the resin was chosen to be clear to show off the carbon weaving.... its sort of like bragging ... as in OH look.. see I used expensive carbon fibre...
 

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its basically the same as fibre glass construction just that carbon fibre is used in place of glass fibre.... the surface that you are painting is the resin that holds the carbon fibre in place...
Yep, and its typically polyester resin (cheapest most cost effective) or epoxy resin (pricey but holds well).
 

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One thing I was wondering .... does carbon fibre material have any sort of signifigant conductivity?

Given it is made with carbon ... and carbon is used for resistors.

Carbon conducts a little ... does it not? And would that amount of conductivity affect antenna performance if used in the antenna support structure.
Doing a quick bit of research into carbon fiber indicates that it will conduct electricity, the resistance depending on the ratio of fiber to resin, and likely the orientation of the fibers also. I think using it for building an antenna would not be the best idea, unless you could get some accurate information and then model the effects.
 
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