Daniel Kamiński’s blog - explains the principles of a GPU-accelerated passive coherent location finder (radar that uses non-cooperative external illumination sources like TV signals), cost a few hundred + a high end GPU, but completeness is low (hard to recreate)
People studying weather, the atmosphere, birds and of course people expecting aircraft. :)
This particular radar is bloody expensive, though - its price tag is about 15 000 euros.
Other fun radar projects, most of them well above my head, so I won’t dare to wade in:
Henrik Forsten: home made polarimetric synthetic aperture radar drone (takes photographic quality radio images of ground, budget several kiloeuros + ability to fly or a high vantage point)
Radar Tutorial - old military guy explains all the concepts, provides many schematics and various formulas
WetterSat - Mobile amateur rain radar - helps you locate rain at 10.5 GHz within a 100 km circle, cost about 1500 euros
Daniel Kamiński’s blog - explains the principles of a GPU-accelerated passive coherent location finder (radar that uses non-cooperative external illumination sources like TV signals), cost a few hundred + a high end GPU, but completeness is low (hard to recreate)