[ok_dad]

It's actually because the antennas need protection from various things like birds and weather, or the antenna itself is classified. Most of those giant radomes are for active or passive radar rather than satellite connections while the satellite antennas are much smaller.

[Eelongate]

I think military dishes aren't necessarily pointed at friendly satellites. They might be eavesdropping on foreign satellites and the domes might serve to conceal which from prying eyes. I suspect large dishes may have utility in such a role, since they might be listening to low power side-band emissions from those satellites (e.g. Van Eck phreaking.)

Either way though, I don't think radomes are meant to conceal the position of the satellites themselves.

[ok_dad]

That could be for some applications here and there, but the major factor is protection (I had a job related to military antennas and radars, but I obviously didn't see every system out there). Those huge golf balls on the water definitely do some sigint and a bit of radar tracking on very long range sources such as missile tests, but everyone knows about those missions:

https://www.staradvertiser.com/2013/04/01/breaking-news/gian...