The ABS NEMA enclosure I’ve used, Bud Industries NBF-32210 is about $15, outdoor rated and a perfect fit for the antenna and equipment. I’ve posted pictures of it on the forum. It works fine indoors and outdoors, open or closed.
The problem it has, as with any sealed moisture proof enclosure, is cooling, if all of the components are to be housed within a closed box. In a marine environment, more so than any other, protection from moisture and salt is of paramount importance for electronics. In some other environments, the moisture may not be an issue.
I operated a ADS-B system with all the gear, including the POE converter, RPi, LNA and RTL dongle in a slightly different Bud enclosure, but with a 2.5" splash proof vent, for several months through all sorts of inclement weather, electrical storms, hailstorms, wind, rain, direct sunlight and 98 degree days, you name it, and it was perfectly fine. Seems the gear ran just hot enough to evaporate any condensation that might have tried to appear inside, but not enough to fry… However, this is South Texas and fairly mild weather, so more Northern, wetter, colder areas, or more humid, hot areas may be a different story for this type of setup.
All of that said, I’ve done a lot of experimenting, design, construction and implementation of RF and computer gear in outdoor enclosures (by trade).
The main problem is the sensitivity of the receiver and CHIP to high temperatures.
My observation on this particular application of the patch antenna, LNA, dongle and CHIP, is that the “best” way to build this system for 24/7/365 operation in an outdoor environment is to separate the antenna/LNA combination from the RTL/CHIP combination.
For temporary or sporadic portable operation, having it all in one box is fine as long as air can circulate.
In a commercial full-time application, I would house it all in one enclosure with solid state cooling. That is quite expensive, but reliable.
Going the separated route, the patch antenna/LNA combo can live very nicely in a modified WiFi patch antenna outdoor case. I have one to play with. Just need to get another Outernet patch antenna in to test.(hint). The RTL/CHIP can live in a ventilated small project case.
Maximum coax length using LMR-240 should be about 25-50 ft. I’ll do some testing by putting that much coax in between the LNA and RTL and get back with the results.
There are other permutations, of course…
One could simply have the RTL/CHIP outside but in a shaded area with ventilated case, and a short coax lead to the antenna/LNA facing skyward.
For seriously dry to slightly wet areas, a simple integrated sunshade over the ventilated equipment enclosure would suffice. This consists of a cover about 1" off the main equipment case, held in place with 1" standoffs to keep the sun off and the air circulating around the box. The sunshade could actually be the antenna/LNA enclosure. Get the idea?
I like the fiberglass radome idea for the marine application, but still there is the problem of heat and accessibility.