Hi Charles, I think you're talking about what some folks call a "paddock shift" system. Having a fixed or mobile coop and a moveable perimeter of electric net fencing. Let the birds terrorize one area and then move them to a new paddock by moving the fence. Here's one post on it but there's more if you search around:
Chicken Paddock System
I think you still need a coop for nighttime protection and possibly some pallet A frames for hawk cover.