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Author Topic: Paint antenna black  (Read 2374 times)
K1BXI
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Posts: 812




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« Reply #15 on: November 05, 2007, 06:39:59 PM »

KE3WD......Let's play nice, Tom didn't "flat state" anything. I would be very careful who I called "rather ignorant, man." When it comes to antennas and anything rf,Tom Rauch, W8JI, has some pretty good credentials. (look them up) In my book, he is one of the best elmers on this site.

John.....K1BXI
 
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ONAIR
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Posts: 1744




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« Reply #16 on: November 05, 2007, 11:19:16 PM »

   Just glue some plastic look alike tree bark on it and stick on some artificial leaves and vines!  The HOA Nazis probably won't know what it is.
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W8JI
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Posts: 9296


WWW

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« Reply #17 on: November 06, 2007, 05:07:26 AM »

KE3WD,

Before you launch you should read.

I didn't say I didn't understand microwaves and dielectrics or the "microwave test". I said I don't understand the fascination with that test.

It really doesn't tell anyone anything useful in most cases. What it tells us is how a material behaves in a strong electromagnetic radiation field at 2 GHz.

It won't tell you a thing about the effect of paint on an antenna at HF.

Let's say I want to test an insulator for an antenna or an amplifier. I pop it in the microwave and it gets hot. Does that mean the insulator will cause loss, get hot, break down and arc, or anything else in the end application? Not at all. It doesn't tell us anything.

I can have an insulator melt that behave just fine in an actual application or I can have one that stays stone cold in the microwave and fails in an antenna or amplifier.

Sorting through materials with a microwave as a "go- no go" failure test is a waste of time unless the end application is for using the material in a microwave oven!!!

Fortunately many people contributing to this thread have actual experience with paint on antennas.

73 Tom
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PD2R
Member

Posts: 131




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« Reply #18 on: November 06, 2007, 07:28:50 AM »

For the right color, take a look at the airforce. They should know.
If you want your antenna to blend in with the sky than don´t use black. Our airforce recently painted their trainer aircraft black so they stand out more against the sky. Only at night black is the color you want to go with, but then it´s dark anyway ;-)
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W4FFM
Member

Posts: 93




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« Reply #19 on: November 06, 2007, 09:22:05 AM »

ONAIR hit the mark about the fake plasic leaves... they REALLY break up the lines and angles.

I bought some 6 foot strands of leaves at a local hobby store and draped them around a 2-meter quarter wave ground plane that I hoisted 25 feet up into a tree. I also threaded the coax thru a couple of strands. You can't see the antenna at all (even if you know it's there) and the coax looks like just another vine going down the side of the tree (looks kinda' like poison ivy, which keeps folks from getting too close).

Make sure that the fake leaves don't use any wire in their construction, of course. The ones I bought were connected by a plastic chain-type of setup.
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NJ2H
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Posts: 6




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« Reply #20 on: November 06, 2007, 10:29:42 AM »

Hy-Gain says its OK to paint their verticals, but to not paint the traps/coils.
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K8AC
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Posts: 1477




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« Reply #21 on: November 18, 2007, 05:17:30 PM »

Those who think flat black is wrong for antennas must not live where there are trees.  If your antennas have a visual background of trees, flat black is as good as camouflage at hiding the antennas.  Of course, if the antenna height exceeds that of the trees, all bets are off.  With the 80 foot trees behind my house, the 60 foot tower and beam, both painted flat black, are invisible from 100 feet away against the background of trees.  I have found that the flat black weathers to grey in strong sunlight over a few years.  Flat black Krylon from WalMart works great and the price is right.
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W4FFM
Member

Posts: 93




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« Reply #22 on: November 18, 2007, 05:39:22 PM »

Rather than waiting for flat black to fade to grey, it's better to start with grey, in my experience. If you take a good look at tree trunks you'll find that they're actually a grey rather than green or brown (aside from patches of moss or lichen). A (relatively) large diameter black object is very easy to pick out against trees... at 100 feet it's harder, but a pattern that breaks up that straight vertical line works better.

This all varies with the trees that you're working against... trees with relatively narrow, light colored trunks, very vertical, with small low visibility horizontal branches lower down (such as the birch) present a vertical stripe pattern of black and white, and I suspect that a flat black pole would work well under those circumstances. A tree with grey bark, and heavy low lying branches (oak, etc), or trees with a lot of green all over (pines) wouldn't work so well with a black pole.

On the other hand, when you're working with a very small diameter object, such as wire, flat black does work best (as long as it's not viewed against the sky).
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