I I made my arbors by setting T-posts (metal fenceposts) and I curved a cattle panel between four T-posts, in an arch. Cattle panels are heavy wire panels, 16 feet long and 4 and a half feet tall.
I used 4 of them to make an arbor, all in a row. There is enough space underneath to drive the lawn tractor thru, and I put them just high enough so I can reach the grapes that hang down from the highest point.
Get a grape cultivation flyer from your local extension office (or online). You WILL need to spray regularly, or you will have a lovely arbor but no fruit. Japanese beetles love grape leaves, and can strip them bare in about 15 minutes. They probably won't kill the vines, but that will hurt yield.