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eHam Forums => Antenna Restrictions => Topic started by: KK4GMU on July 24, 2022, 01:47:39 PM

Title: Paint on a yagi
Post by: KK4GMU on July 24, 2022, 01:47:39 PM
A separate "stealth yagi" topic to satisfy my HOA:

I read that if an antenna is to be painted to help it become stealthier, it should be painted with a "non-metallic" paint.

Does that same advice apply to a metallic antenna?  It's already metal.  It's counter-intuitive to believe that a 0.2mm of metallic paint can adversely affect the performance of an already metallic antenna.

What is the best advice regarding painting a yagi?
Title: Re: Paint on a yagi,
Post by: K6AER on July 24, 2022, 07:34:12 PM
I have had SteppIR antennas for over 20 years . After ten years the color is gone from the fiber glass poles and I will just paint the antenna with acrylic paint. The tuning lengths don't change.

As far as painting an antenna to make it stealth, it never works.
Title: Re: Paint on a yagi
Post by: K0UA on July 24, 2022, 08:49:48 PM
I have painted mine with clear Krylon for years. Just to help prevent corrosion. I have painted the fiberglass portion of my ancient Hustler G6 2 meter antenna with gray paint to keep it from delaminating. Doesn't hurt a thing.
Title: Re: Paint on a yagi
Post by: W0RW on July 25, 2022, 05:42:44 AM
i always paint my T Hunt yagis black.
It keeps the jammers from seeing it until it is too late.
i paint my base antennas green to blend in with the trees.
Paul   w0rw
Title: Re: Paint on a yagi
Post by: WB6BYU on July 25, 2022, 09:51:41 AM
Metalic paint may make a difference if it creates a short across an
insulator, or creates a shield on the outside of the fiberglass tube
that protects a VHF/UHF antenna.

But the "metalic" paints I've seen aren't actually conductive,
they just have sparkles of metal in them.  It might produce
some dielectric loading effects in certain cases that would
shift the resonant frequency slightly, but otherwise I doubt
it would make much difference.


Probably isn't the best choice for making the antenna less
obvious, but I don't know the background color scheme of
your house...
Title: Re: Paint on a yagi
Post by: WA3SKN on July 25, 2022, 11:47:16 AM
The real question is... "is the paint conductive?".
Say you have a plumber's delight constructed yagi... metal elements with metal boom and connected.  It will do no harm to put conductive paint on the parts.
Now if you have insulated parts and you put conductive paint on you might have a problem.
Make a test patch with the paint and let it dry, then measure the DC resistance with an ohmmeter.  As long as the resistance is at least 10 times the impedance you are bridging you should be OK.
But paint rarely "hides" an antenna. So you should ask "do I have to?" when painting antennas.
Remember it is messy to get off!

-Mike.
Title: Re: Paint on a yagi
Post by: W1RKW on July 25, 2022, 12:40:58 PM
think red and white AM radio tower.
Title: Re: Paint on a yagi
Post by: W1VT on July 26, 2022, 07:00:50 AM
I recall getting a report that Rustoleum camo paint caused a high SWR about a year ago.
Title: Re: Paint on a yagi
Post by: K1KIM on July 26, 2022, 07:40:19 AM
"Metallic" paint on a "metal"antenna has no effect other than to change the color.

I think the jury is out on whether it affects the radiation of a fiberglass antenna (which is just a metal antenna on a fiberglass sleeve).

The only way I have seen paint to be conductive is to make my own to shield the cavities on an electric guitar. That paint I make of carbon powder and clear lacquer. Heavy on the carbon!
Title: Re: Paint on a yagi
Post by: GEORGEMINK on December 11, 2022, 06:09:35 AM
I'm living under a restrictive HOA and have been inclined to keep everything in the attic. But I just purchased a Moonraker GPA-80 and have it mounted over a 5 gallon concrete filled bucket on a removable PVC pipe in my back yard. I thought at 20' and without any traps that the skinny little antenna would not be noticeable but even with my 6' privacy fence it stands out pretty bad from the road. I think mainly because it's shinny, even at night the street lights reflect off of it.

So, I'm going to paint it with some flat paint. Just wondering who hear has had any experience with trying to "Camo" their antenna and how did it work out? what color did you use? I have several cans of camo colored paint already in FDE, Dark Brown, and Olive Drab. Black has been mentioned too. 
Title: Re: Paint on a yagi
Post by: W6IBU on December 11, 2022, 08:29:37 AM
If you're worried about conductivity, test the paint in a microwave for a bit and see if it gets hot.  I've heard that works.

73, Paul, W6IBU
Title: Re: Paint on a yagi
Post by: WB6BYU on December 11, 2022, 08:41:36 AM
Generally I’d use black, but if the background
neighbors will see it against is mostly trees,
then a brown/green paint job might work.

The wire HF antenna on my roof is #26 brown /
green insulated hookup wire.  When hams come
to visit I walk them right under it and tell them
to look up.  It is very difficult to see from the
road unless the sunlight glints on it, or it
has a coating of frost or snow.
Title: Re: Paint on a yagi
Post by: W7CXC on December 11, 2022, 08:48:37 AM
Flat battle ship grey is quite effective. (Krylon)
Title: Re: Paint on a yagi
Post by: K5LXP on December 11, 2022, 11:20:39 AM
I painted a vertical flat black for a guy that had it set up in an HOA.  It was literally impossible to see from the street, it vanished against the vegetation and structures.  But a yagi up in the sky is pretty hard to hide.  There are some commercial verticals that come with a sky-blue radome I've seen but that's like the fake evergreen tree cell phone antennas.  Might be less visually "offensive" but there's no hiding an antenna on a mast or tower.

Mark K5LXP
Albuquerque, NM
Title: Re: Paint on a yagi
Post by: K5TED on December 11, 2022, 11:24:55 AM
I use self etching spray primer on my aluminum and white fiberglass verticals. It's a flat gray/green, and in mostly invisible from a block away. Not conductive to any extent that would affect the antenna performance that I can tell.

https://painttopics.com/what-is-self-etching-primer/
Title: Re: Paint on a yagi
Post by: N2SR on December 11, 2022, 04:29:52 PM
fluorescent orange
Title: Re: Paint on a yagi
Post by: KF5KWO on December 12, 2022, 05:18:10 AM
I put self-etching primer on my MFJ Moxon (aluminum elements) then spray painted it a dark olive green that I got from Lowe’s, one of the camo blends. The antenna is out there in the trees. We have fairly good concealment from the street, but that aluminum would have stuck out immediately.
Title: Re: Paint on a yagi
Post by: KK4GMU on December 12, 2022, 01:08:32 PM
Did the self-etching primer create an even flatter, less visible effect than just flat paint alone would?
Title: Re: Paint on a yagi
Post by: KF5KWO on December 12, 2022, 05:17:15 PM
@KK4GMU - the primer was to provide a good surface for the olive drab paint to adhere to. Primer was white or gray, can’t remember exactly. Before applying the primer, I sanded the aluminum elements of the antenna to help the primer adhere to it. The aluminum has a shiny sheen to it before sanding. After that, a coat of the primer or two, dry overnight, then the olive drab spray paint.
Title: Re: Paint on a yagi
Post by: GEORGEMINK on December 17, 2022, 03:12:44 PM
Flat battle ship grey is quite effective. (Krylon)

Just a follow up. I painted my 20' vertical today using the camo paint I already had on hand. It helped with the glare and shine of the bare metal but appears really dark against the sky. I imagine that it will not be seen now at night and is a little less obvious during the day but I think the suggestion of battle ship grey is probably spot on. So I'll try that next weekend and report back.
Title: Re: Paint on a yagi
Post by: KC3TEC on December 27, 2022, 06:14:12 PM
If your paint contains metal such as lead it may affect the propagation a little but not by much.
If you are running a boatload of power the paint may melt or smoke a lot.
That would certainly attract unwanted attention.
The problem with coats of paint is the tend to hold in heat a bit.
Title: Re: Paint on a yagi
Post by: WA8NVW on December 29, 2022, 02:07:52 PM
Camo paint or fabric is intended to hide reflections from shiny stuff under a tree canopy.  Back even before the turn of the century, manufacturers of commercial two-way vertical antennas inside fiberglass radomes determined that a light creamy-blue was the color least likely to contrast and stand out against the sky as a background.
White jacketed #18 to #12 stranded wire is hardest for the HOA folks to find against a bright sky.  For hiding rigid antenna elements or structure, dull the (aluminum) metal surface with steel wool, then apply a coat of light sky blue latex paint.  It's non-conductive and does not smoke, burn, or melt.  No, we as consumers generally cannot buy lead based paints any more.
Title: Re: Paint on a yagi
Post by: AA4HA on January 11, 2023, 07:53:24 AM
One of the best I have seen for low-visibility is a powder-blue/grey paint with a flat finish.

We sometimes use it on radomes for microwave antennas when they are backed by the open sky. There are some colinears (fiberglass vertical stick) antennas that also use that color. A few times when refurbishing a site I would have them lower the antenna down so we could hand sand and refinish the fiberglass surface (also clear any drain weep holes and give a good scrub on the type-N connector to remove butyl tape residue.) I would just run down to the local hardware store and find a few rattle cans of flat blue/grey or our guys would have some extras on their truck.

(that was also a good time to sweep the antenna, colinear omni's have a terrible problem with lightning strikes blowing open the antenna in the middle of the stacked elements and the gain disappears or the antenna pattern turns in to a cloud-burner).

Of course, if your antenna is down in the trees than something that blends in with that particular background.

As far as painting goes; From a work perspective where we are constantly putting up Yagi antennas one of the nicer finishes is a powder coat black. The antenna works just fine through the finish and the flat black color seems to have some added benefit of letting the antenna warm up slightly in the sunlight to melt off any frost or ice. (Yagi antennas loose their Yagi-ness when ice builds up)
Title: Re: Paint on a yagi
Post by: GEORGEMINK on January 11, 2023, 09:24:03 AM
One of the best I have seen for low-visibility is a powder-blue/grey paint with a flat finish.

Blue/grey was the same conclusion I came too and will try it out. Since I have not received any negative feedback from my neighbors or HOA after putting up the 19' vertical on my privacy fence I've decided to take it down and put up a 25' support and run a 84' end fed to it in a slopper configuration. I purchase grey wire and paracord for the job. I think that will be as stealthy as I'm going to get.