Alan Stanczik sent me the link to this interesting archive video about the ‘BUPS’. According to this, the AN/UPN1 & 2 would have been the actual BUPS, and not what most collectors commonly refer to as the BUPS, i.e. the long bag with the telescopic antenna and ground stakes you can see in the photos below, which is actually the AN/CRN-12. This was a post-war device (the manual is dated 1951).
Interestingly though, the paratrooper on the right carries the bag of CRN-12 antenna, along with the CRN-4 beacon, which came in the two padded bags you see here. The CRN-4 was a WWII device and it was used by American pathfinders during Operation Market Garden. From after action reports of the 101st Airborne, we do know that the antenna originally intended for the CRN-4 was replaced with another one after the drop on Holland, but I haven’t been able to find any further details about this.
The AN/UPN-1 & 2 is quite a large device and not really field portable, as you can see in this video:
If you know more about this, please comment here, or send me an email.