The problem is, radar returns decline with the 4th power of distance - so if you can detect a 1m square at 100km, you can detect a 1cm square at 10km and a 0.1m

The problem is, radar returns decline with the 4th power of distance - so if you can detect a 1m square at 100km, you can detect a 1cm square at 10km and a 0.1mm square at 1km. Yeah, a marble is fantastic in comparison to a barn door - but that 4th power cuts both ways.