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Non-conductive paint

Discussion in 'General Technical Questions and Answers' started by K4GAP, Aug 26, 2003.

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  1. K4GAP

    K4GAP Ham Member QRZ Page

    I am building some small (70cm) quads using 3/4 in. pvc for the boom and 3/8 in. fiberglass rods for the spreaders. I would like to protect the antenna from the effects of the sun and weather (as much as is possible to do). Does anyone know of a paint that is non-conductive that I could coat the antenna boom and spreaders with?

    Gary, K4Gap
  2. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    Water base latex paint, unless metallic in finish, is very non-conductive and very weather/UV resistant, adheres well and dries in minutes. I'd just use house paint.
  3. KA4GEH

    KA4GEH Ham Member QRZ Page

    I would not think that painting the antenna support structure should be a problem no matter what kind of paint you use.  The problem is not so much that a paint is conductive, but that the pigment (the coloring matter) in the paint is made from ground up metallic compounds, such as Titanium Dioxide, Iron Oxide, Zinc Oxide, etc.  Many of these compounds are not at all conductive, even if they are metal based.  For instance, Aluminum Oxide is a good insulator.  The problem is that some pigments may interfere with the transmission of RF energy.

    This is usually only a concern when one paints the exterior surface of an antenna enclosure, such as the radome on an aircraft that covers and protects the radar antenna.  If you were to totally enclose your antenna in a piece of PVC pipe, as is done with some J-Pole designs, and then paint the exterior of the pipe you might need to have some concern over the pigment used in the paint.  The issue is transmissivity.  How transparent is the paint pigment to RF at the frequency of interest? In the design you describe, all your radiating elements are exposed and do not get painted anyway, so transmissivity is not going to be an issue.

    Pick a nice color, paint one and see what happens. If it really concerns you, contact a paint manufacturer and ask about colors in his line that are made using organic (non-metallic) pigments. If you get the right guy, he may be able to recommend specific products in his line that are made specificly for painting antennas in your frequency range. Alternately, use a clear epoxy or polyurethane, that has no pigment. These can be obtained that do have UV inhibitors.

    Above all, have fun!
  4. W7EET

    W7EET Ham Member QRZ Page

    Use epoxy paint.
    kg7wd [​IMG]
  5. K9KJM

    K9KJM Ham Member QRZ Page

    The type of paint has very little to do
    with it, Except that water base latex
    usually has lots less metallic than
    other types...... Some types of epoxy
    have lots of metallic particles in it.
    Some of these paints are NO GOOD
    to use on for example a fiberglass
    radom over a gain type antenna.
    The zinc base types are a good example.
    They are really small particles of
    zinc in a liquid paint base.
    Test a small panel of non conductor,
    (Cardboard, etc) in the microwave
    oven to make sure it does not heat up.
    THEN paint that same piece with the
    intended paint. It should NOT heat up
    in a minute or so in the microwave....
    (This is one of those tests much better
    done when the XYL is not around.......)
    Most all "clear coat" type paints are
    non conducting and should be OK....
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