Painting the antenna can be done as long as the paint does not have any metallic content. Also, depending on the antenna, be sure that the radome of the antenna is not damaged by the content of the paint (petroleum based paints would likely damage this). I would think a water-based latex with no metallic contents would be totally acceptable, but Id still test on a small portion of the antenna first for potential decomposition of the radome. I did find this URL for a commercial antenna vendor you might find useful.
http://www.decibelproducts.com
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