Completely excellent mysterious question. Now that I see beowulff’s post I think picunurse is right.
The things sticking up on the four corners wouldn’t be radiators themselves, they’re not insulated and so forth. But there are what could be radiators on the sides of the poles opposite the tower centerline. This wouldn’t be right for a phased array, but would be right for something that works like a cell tower does, with separate lobes coming off of separate radiator assemblies. Note, it’s not a cell tower, those radiators are taller and would be for longer wavelengths, but the principle would be similar. All that being said, now that “radar tower awaiting completion” is in the running, I’d guess the poles on the corners are just for holding warning lights up there, and wonder if they’re temporary.
Given that most airports already have a very high-powered rotating radar array operating near the tower, perhaps this is a receive-only antenna for some type of transmission that the planes generate? It’s got four elements, so it could be used as an interferometer to verify direction.
I am involved in tower construction, and can tell you that the devices on the corners are not lightning rods. You can see the feed lines attached via standoffs to the tower legs in one of those pictures, so they are some sort of antenna. The tower itsself seems fairly new, and probably not a legacy tower from the old AT&T microwave relay system or the like. The fact that it has a nice top deck and stairs as opposed to being a 3 legged self supprorting tower or monopole with step bolts and safety climb would indicate to me that there is or will be equipment installed on the deck itsself. The tower will probably be used for a variety of equipment, not just a single system.
It looks like the question has been (mostly) answered, so I wanted to chime in that that reminds me of the lightning observation towers at Langmuir, a lightning research facility in New Mexico. We used to climb on top of them during electrical storms. It was pretty neat being so close to the lightning… although I’m not sure that was the safest thing we did in college! :smack: (Heck, I’m not even sure they were observation decks. Probably not. :eek: )
The four corner poles have the cables on standoffs from the poles. Would they do that for power cords to the lights? Maybe the cables are themselves antennae.
The top level of the tower has a lot more bracing than the other levels. Does that seem to indicate something very heavy will go on the top deck?
Alert, alert. Any doper planning to fly out of or into O’Hare, is hereby directed to take a photo of the top of this radar antenna tower. There. No more conjecture.
Sorry for the delayed reply, all. I’m on vacation at the moment and with search down, I haven’t been keeping up with my SDMB.
The tower construction is brand new. And I saw a nearly identical one while flying into Salt Lake City last weekend. It had a red/orange rotating radar antenna on it. I just hope they aim it high enough so I don’t get RF buzzed each time I pass by (probably 15 times a week).
Just looking at that pic makes me dizzy. Cool tower, tho.
