I would think that a non-metallic paint used on an element would cause a slowing of the accelerating charge down the wire/element, as insulation does -- to some extent. To what extent I have no idea, just my educated guess. For a test -- take a resonant element, spray it with non-metallic paint, let dry and then see how the resonance has changed. The current flow still occurs in the original metal element.
Painting with metallic based paint -- as long as the paint covers only the metalic radiating element, it would act as a conductor....now to what efficiency that sprayed on conductor perfoms is the million dollar question and, also, deserves some investigation. Take a metal tube, make it resonant at some frequency, then spray the element with metallic paint. Let dry and see how the resonance and feed impedance changes, if at all. It might add some loss resistance to the element and due to the skin effect might just take the majority of the RF current flow down the element. With the added resistance it would add bandwidth. Higher loss, but a wider SWR operational bandwidth. Effecting gain and efficiency. Now, spraying a metallic or lead based paint over every surface of the antenna AND its' support structure is looking for trouble, as Robert pointed out on the police car. They essentially generated a Wheeler Cap....the inverse of a Radome. A fun topic, enjoyed reading all of the takes and most were valid IMHO -- Just my $.02....W5RH. Rick Hiller *The Radio Hotel* -- W5RH On Wed, Feb 22, 2017 at 3:16 PM, Robert Polinski via BVARC <[email protected]> wrote: > Paint is ok, do not use auto paint or metallic paint, or paint with lead. > Child safe paint assures no metals are used. No hi temp paints ether. > Another option is to use heat shrink tubing. Robert > > > > *From:* BVARC [mailto:[email protected]] *On Behalf Of *Tom Watson > via BVARC > *Sent:* Wednesday, February 22, 2017 3:05 PM > *To:* 'BRAZOS VALLEY AMATEUR RADIO CLUB' <[email protected]> > *Cc:* Tom Watson <[email protected]> > *Subject:* Re: [BVARC] Paint and antennas > > > > Gayle, > > > > I’ve been researching the exact same question, but have not found a > definitive answer. Some think it makes no difference; others are skeptical. > Below is an exchange I had recently with Al Andzik (WB0TGE) about painting > his “Mighty Woof” copper tube 2m/70 cm design ( > http://www.hamradioschool.com/wbotges-mighty-woof-2m440-mhz- > dual-band-fan-dipole/ ). I am building this antenna and will test it > with and without paint by the end of March. I’ll post the results. > > > > Tom Watson, WZ8Q > > ------------------------------------------------------------ > ---------------- > > *From:* Al Andzik [mailto:[email protected] <[email protected]>] > *Sent:* Friday, February 10, 2017 7:39 PM > *To:* Tom Watson > *Subject:* Re: Your "Mighty Woof" 2m/440 MHz fan dipole... > > > > Really can't say if paint will affect characteristics. You might try doing > some SWR measurements un-painted then paint maybe one element and see if > things change. If they do, you can clean it off. > > > > Also if a dark color is what you want, perhaps some "cold" gun bluing > solution might work instead of paint. You wouldn't have a coating over the > metal but it will just change the color. Usually the stuff is for steel, > but it might work on copper in some manner too. > > > On Feb 10, 2017, at 4:56 PM, Tom Watson <[email protected]> wrote: > > Al, > > > > Have you heard of anyone painting this antenna? I live in an > HOA-controlled area, but members of the architectural committee don’t see > so well and I believe that if I paint this antenna dark gray, no one will > see it. So far, I haven’t found any discussions that suggest that an > antenna cannot be painted or that doing so will cause a significant > decrease in performance. But I want to be sure before proceeding with > paint. > > > > Also, I plan to run the transmission line inside a 15’, 1-3/8” diameter > steel tube attached to a wooden fence. Is it possible that the tube will > provide enough of a choke effect, or do you think the 4 or 5 turns of coax > for that purpose will still be necessary? > > > > Thanks again for your help, > > > > Tom Watson, WZ8Q > > > > *From:* BVARC [mailto:[email protected] <[email protected]>] *On > Behalf Of *Gayle Dotts via BVARC > *Sent:* Wednesday, February 22, 2017 2:31 PM > *To:* BRAZOS VALLEY AMATEUR RADIO CLUB > *Cc:* Gayle Dotts > *Subject:* [BVARC] Paint and antennas > > > > Can an tube antenna say a beam or Yagi, be painted for camoflage purposes > and not loose any Tx or Rx characteristics by painting it? > > > > Gayle > > KF5LVZ > > _______________________________________________ > BVARC mailing list > [email protected] > http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org > >
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