[NLRS] Slightly off topic, strange airplane

[W0ZQ at aol.com]

When I went outside today to get my mail, I saw a strange airplane that  
perhaps someone out there in NLRS can explain to me
 
The plane was a two engine (prop) of fair size, say about 1/2 the size  of a 
C130.   It did not appear to be military.   It was  flying west to east at say 
2,000' or so, somewhat low.     What caught my attention was the large 
horizontal loop "antenna" (I'm assuming  its an antenna).   There was a strut out 
the back of the tail and a  second strut out the front of the nose and a cable 
(wire?) strung all the way  around outside of the plane; from the tip of the 
nose strut to the tip of the  left wing, to the tip of the tail strut, to the 
tip of the right wing, back to  the tip of the nose strut.   It looked like 
someone had taken a pencil  and drawn a box all around the very outside of the 
airplane.    A  flying horizontal loop.    Like I said, it look strange and I've  
never seen anything like it before.
 
My guess is its some kind of downward looking magnetic detection  device ... 
perhaps for pipelines or ???.    Like I said, I don't  think it was military.
 
Of course my thoughts were about how it would load on say, 6m, or perhaps  
160m.
 
73, Jon
W0ZQ