Maybe, probably, but why would you?
Personally, I would not paint an antenna. It’s possible that it wouldn’t do any harm, but it’s very hard to know what’s being used to give paint its color. Often times, a metal like chromium, iron, cobalt, or copper is used for bright, sharp colors and the flakes of metal inside the paint can make an antenna less effective. On the other hand, if synthetic or vegetable pigments are used, they’re going to have very little effect on an antenna. As I said, how would you know?
You may have noticed that some antennas like our Televes line have bright orange plastic in places, and I suspect that if you didn’t like that particular part, you could paint those and you’d probably be fine. If you’re really an expert on antennas and you can tell which parts are actually used for reception and which parts simply direct the signal to the receiving elements, you could probably paint the parts used there. Again though this seems like a lot of work and you would probably end up guessing wrong at some point and ruining something.
If you have an antenna encased in a white “radome” you are best off not painting at all because the actual antenna is encased in plastic and there’s no guarantee that the color you’ve chosen would let signals in. In the case of larger antennas that have brand names on them, the brand name is either located somewhere that it won’t make a difference, or the paint or decal that’s used has been extensively tested to make sure that it won’t negatively affect reception.
Here’s the difference between painting a dish and painting an antenna. When people talk about painting a dish, they’re usually talking about painting the reflector, which means it doesn’t really matter what color is being used as long as the surface just bounces the signal to the front of the dish. With an antenna, you’re talking about the signal having to make it through the paint and there’s a very good chance it’s not going to.
Rather than painting an antenna, I’d almost always recommend buying a new one, or if the problem is that it has developed an unsightly black patina, you can use a metal polish to remove that. Just keep in mind that it will return and that it’s not hurting your reception.