My job sent me to a remote island off the west coast. I flew on a 1950s vintage De Havilland Beaver float plane. We flew over this installation.


I rented a car on the island and drove out to have a better look.
That is a four story building inside the circle.

 

I am thinking it might be an aeronautical VOR antenna. A little on the large size though, they are not that big normally.

 

I didn't know about Circularly Disposed Antenna Array (CDAA), having Googled it, I think Delta Prime is right.

 

https://en.wikipedia.org/wiki/AN/FRD-10 ???

 

Its on Haida Gwaii just north of Masset.
Its a Canadian Armed Forces Installation.