you could always rig up a small alarm on your gate , with a presure switch and a mondeo car horn to an old car battery hidden in the corner , my mate did this to his garage to stop people trying to brake in and pinch his dirt bikes it worked no one ever came back after the first attemped . . . it woke his street up at least 6 of his neighbours who all looked out the window to see them scarpering over his back fence