Raytheon’s New Radar Could Help Bring Flying Cars to Our Cities

Like many cliches, "flying under the radar" has a literal, real-world history. As the new object-detection technology proliferated in the years after World War II, military pilots knew it had trouble seeing things at low altitudes, where buildings and hills severely limit its range. And so pilots would hug the terrain, flying beneath the radio waves that would detect their presence.

Eric Adams

https://www.wired.com/story/raytheon-radar-drones/