Key question: What is the practical long range of a wide area GPS jamming device?

Short-range GPS jammers are commercially available. A typical model is a 0.960 watt output power jamming device designed to completely disable GPS signals within 15 meters up to 40 meters away. Using a cheap 3 kW portable generator for about $500, and an old fiberglass body cube van for about $10,000, was able to completely shut down a circular area of 1.5 km in diameter from GPS service.