Well.. YOu can get the UHF Barrell connectors (Feed throughs) in assorted lengths.. I have one that's long enough to go all the way through my roof.. These are not that far removed from 1/2 inch so if you want to go through the wall you might try this.
Get one at least 2"-3" longer than your wall is thick Get at least 4 nuts for it. (A couple of washers might not be bad either)
Now. drill the proper size hole, shove it in and position your nuts, NOTE you want more left over threads than you need by at least a half inch. Loctite the outer nut, remove the inner nut and pull it back about an inch or so, Let sit, 4 hours (Locktite sets fully in that time.
Cover the wall side threads with GOOP sealant (Most any flavor of GOOP will do here) shove it in place, add inner nut, loctite optional.
Now add more GOOP to cover the outside nut Let sit over night
Now slip a shower trim ring (the kind that slides over the 1/2 inch shower arm) and add a 2nd nut (Washer optional) to hold it in place, This dresses up the install, on the outside, if you wish locktite GREEN the nut (That's the weakest version) but frankly.. I'd not.
Do the same on the inside