Viron said
..The photo worked well, but I couldn't make out how you attached the wire to the top of the steel posts...    

Its not wire, its 1" thin-wall galvanized steel electrical conduit.

Not mine, but same process:

For my blackberries I'm thinking of using 8' T-posts driven 2' in and then attaching 3/4" conduit using 2 hole hangers bolted on with nuts and lock washers.  It will require drilling holes through the T-posts.

Dubyadee said
I like the idea of the 1" conduit.  I'd suggest flattening each end of the conduit with a hammer or by clamping in a vise and then drill a 1/4" or 5/16" bolt hole to bolt securely to the T-post.  I think the conduit might slip out of those couplers when a heavy load of vines accumulates on the conduit.

Hmm, I'd thought I'd replied but I must not have hit "enter".

Flattening the end isn't something I'd considered but is a good idea.  Although In order for the conduit to pull out of the fitting it would have to shear the screw or tear through the conduit or fitting wall.  The screw holding the conduit in place isn't a set screw, it pierces the wall of the conduit.

I suppose flattening the ends would get 2 wall thicknesses of purchase on the bolt.

If/when I bolt things to the T-posts directly I'll need to figure out how to pound them without allowing them to rotate.  I'm not good at maintaining the orientation while I drive them.