How Can Fighter Jets Evade Radar?

In the past, the main way for fighter jets to avoid radar was to fly below it, but the development of look-down radars able to pick out fighter jets from the clutter of the ground has dramatically reduced the effectiveness of that. Today, modern fighter jets, like the Lockheed MartinF-35, avoid being picked up on radar with a broad spectrum of stealth technologies. 6th-generational aircraft, like the F-47 are being built for all-aspect stealth.