[Dalek Prime]

Some types of wood are particularly amenable to bending, after being heated/steamed. I saw this on the show "Victorian Farm". Back then, farmers crafted many things with wood. How would that be as a frame? Or bamboo? Just need to find a supplier, or a local craftsman. I know that, in Toronto at least, there are many craftsmen working out of Queen's Quay. My sister took a class or two.

I'm trying to remember what type they used for carriage wheels. Ash, perhaps? Willow? Those wheels held up to some major weathering, and much mud in travel. A lot less wear as a frame than a wheel, especially if treated. Then the reflector rods can be clamped onto the frame, following it's curvature.

Anyways, might be a worthwhile material for a frame that has special requirements. eg A parabolic section.

 

[stampeder]

300ohm has discussed the problems with wood a few times in the past, so its use is discouraged. To summarize, while wood is theoretically a dielectric, a sufficient amount of moisture found in almost any piece of wood may have a negative impact on antenna performance by introducing signal reflections/refractions.

Antenna builders are best to use these options, discussed in detail:

ABS, PVC, other plastics and Rubber for structural parts

Best Metals for Antennas: Performance, Soldering, Welding, Bending, Working

 

[Dalek Prime]

Moisture.... Rats! I can't believe I forgot about that. *Gives head a shake.*

 

[ota_canuck]

Even aside from moisture concerns, wood used in a dry attic would still not be the best choice of materials for racking and supports, because wood is so dense that it could hamper the path of signals, cause deflections, etc.

Though bamboo could be very interesting and a reasonable experimental choice of material to build a frame, because even though bamboo is not conductive, it is sensitive to radio and microwave frequency and could possibly serve a purpose similar as a Narod does.

 

[300ohm]

Or bamboo?

Ive got oodles of that stuff growing, so I can tell you a lot about it, from growing it to working with it. Its great stuff for tomato stakes and cages, but not really for antenna purposes. Grey electrical pvc is much better, and even cheaper than buying properly treated bamboo of the same size and length.

Ash, perhaps? Willow?

Willow rots very quickly. The best woods against rot are teak and dark mahogany (very pricey), cypress, white (not red) oak, redwoods, black locust.

Treated bamboo is also very rot resistant. I treat my bamboo by using 1 tablespoon of borax per gallon of water in a bucket. Cut the bamboo, leave the leaves on, and place the ends in the bucket for about 2 weeks. The leaves help draw the water-borax up the stalk.
Even untreated, bamboo will last in the ground for a growing season.

 

[Dalek Prime]

You have bamboo growing in Delaware, 300ohm? How thick? (The individual bamboo, not the thickets.) One thing's for sure; with lots of bamboo, you'll never run out of scaffolding material. Kind of a shame we can't be more green with our frames though. Ah well.

Good bit on Ash uses here. Strong, yet elastic.

http://en.wikipedia.org/wiki/Fraxinus#Uses

 

[300ohm]

The variety I have grows 3/4" to 1 1/2" in diameter, and grows up to about 25 - 30 ft tall. It spreads by runners in the spring, and is pretty invasive. It certainly has no problem tolerating temps down to 2 degrees Farenheit at least.
When the bamboo pops out of the ground, thats the diameter it will be. Its very thin walled then and as it ages, it grows thickness from the outside in, unlike other woods. In 5 years, its as thick inside as its ever going to get, and the shoot dies in about 7 to 8 years.

There are lots of bamboo varieties, and Im sure theres quite a few varieties that would do well in Ontario.

When I join two pieces together, I dont lash. Thats too time consuming. I either use duct tape, heh, or an old 8 to 12 penny nail. Drill a hole through both pieces, insert nail, and bend over the pointy end with large water pump pliers until compressed. Quick and sturdy if joined at the bamboo sections.

When the shoot first pops out of the ground, you can eat it. It tastes a little bit like corn.

When the shoot is 3 to 9 months old, its good material for basket weaving.

The shoot need to be at least 3 years old for structural stuff.

 

[ota_canuck]

or an old 8 to 12 penny nail

I'd say that may cause reception interference, ha!
___________________

I wonder if a well designed chair could get some reception?

BTW: Bamboo grows almost anywhere it can. It's very invasive in our gardens at the side of our house here in the escarpment area.
You can't seem to kill the stuff!

 

[Dalek Prime]

Very cool. If I had the bamboo supply you have, I don't think I'd ever buy furniture again. Just cushions. I have to look into growing it here.

Oh, I hope no one minds, but as this is my 100th post... Hopefully, I've added as much as taken from the dialogue thus far.

Okay. It's out of my system now.

 

[300ohm]

If I had the bamboo supply you have, I don't think I'd ever buy furniture again. Just cushions.

Well, its not all that easy to work with. And then you walk into a place like Pier 1 imports and see one built and already with cushions for very little. Then you realize youve been working for 25 cents an hour, heh.

 

[stampeder]

Not "wood" per se: but as 300ohm has said in the past, certain types of laminate (manufactured wood-like product for flooring, deck lumber, etc.) might be usable for OTA gear. Pressure-treated lumber usually contains metallic elements (copper quat, etc.) so will not do.

 

[Dalek Prime]

So many things I never expected when I first gained an interest in antennas. So much to consider. Geometry and electro-magnetics, of course. But also materials, weather. I'm very grateful for all the knowledge you pioneers and veterans share with me, and others like me.

Cheers all.

 

[300ohm]

Pressure-treated lumber usually contains metallic elements (copper quat, etc.) so will not do.

I think theyve outlawed copper based preservative, which IMO was superior. Now I think theyre using borax and arsenic stuff.

 

[ota_canuck]

It baffles me to think that they have banned the use of copper in treatment processes and substituted with arsenic. That's like banning copper water pipes, for plastics PVC/ABS which produce carcinogens.

Speaking of plastics ABS. There is a process of etching injection molded ABS parts and then metal coating the treated plastic surface with chrome/copper/brass/aluminium/tin, etc. Would that work a suitable antenna element material in our plastic world?

 

[Dalek Prime]

That would certainly take some of the expense out of copper elements, should the metal be layered on top. Holl_ands mentioned conductive aluminium tape to me a while back, and reports that wrapping it around element structures of otherwise non-conductive material works quite well. Similar idea.

Is there no manufacturer who does this? Sounds like an opportunity to me.

 

[ota_canuck]

It's a common metallic plating process for household fixtures and appliances. Many plastic plumbing faucets are plated with chrome/brass/copper/and even pewter finishes.

 

[ota_canuck]

Here's something else that could become an interesting advancement for antennas.

They devised one treatment that made the fibers attract water, and another that made the fibers repel water. They found they could also make the surfaces attract or repel oil. Depending on what polymer they start with, the fibers can also be made to conduct electricity.
http://www.physorg.com/news102265088.html

Could you imagine an antenna that could essentially be genetically programed for a specific level of magnetic response, being electrically conductive and water repellant? Wow! That would create opportunity for HUGE advancements in the antenna development/design industry for having the ability to be tune for specific frequencies.

Here is another link that discusses conductive/magnetic plastics:
http://www.chem.unl.edu/rajca/futurist.html

In case your wonder. I worked with these materials during my employment at Duracell's research facility in Mississauga. These conductive polymers are capable of handling almost all low voltages, low amperage applications, with the obvious exclusion of direct contact in heating devices.

This is not just wishfull thoughts, this is the reality of what's in store in the near future. Actually, these technologies are available today, with the immediate focus being on processor hardware made of plastics. This technology could soon replace the use of non-recyclable silcon parts. It makes the components of electrical devices more enviro-friendly in the sense of recyclability.

 

[300ohm]

Many plastic plumbing faucets are plated with chrome

Yep. I installed a 100% plastic faucet in the utility bathroom about 15 years ago, and still going strong. Its a Sterling brand, chrome plated and it has no washers or any replaceable parts. It was about $12, and if it goes bad, its meant to be replaced completely.

Its held up better than any metal faucet that Ive ever had. There is no pitting or anything on the chrome (unlike with chrome plated brass faucets Ive had there) and it still looks like new. (the clear plastic handles are getting a bit yellowed and dirty though) Ive never gotten any drips from from it, unlike with metal faucets with rubber washers which I had to replace the washers yearly.

I just measured the chrome finish, and its not 100% conductive, ie there is some small resistance showing even at 1" between the probes.

 

[ota_canuck]

Though it's not 100% conductive, it meets the required level of conductivity for grounding/static discharges of water faucets. The coating on faucets may contain a lacquer component [that lacquer actually rises to the surface during the coating process to provide a shiny durable finish] to resist corrosion from other water-bourne metals and salts. You may have seen some older plastic faucets that been worn or damaged and the damaged areas may be prone to getting a green colour deposit buildup. If you lightly sand the surface, you may find a slight increase in the suface conductivity. If you check it with a magnet, even though the coating is only a few microns deep, there should be some slight but noticable magnetic properties.

________________

So we've really managed to derail this thread from the topic of wood to the development of high-tech electro-magnetic polymers

 

[jflarin]

I think theyve outlawed copper based preservative, which IMO was superior. Now I think theyre using borax and arsenic stuff.

In Canada they outlawed copper-arsenic mix and replaced it with copper-quarternary stuff. The copper is still present, it's the arsenic that's gone.

Still farmers and utilities (for theirs posts) are still allowed to use arsenic.

jf