No. Lol. You don't get to make up the rules of physics. It's obviously untrue that if the Earth were flat, radar would be able to travel unlimited distances (for one thing, I know the Earth is flat and radar can't travel unlimited distances). However, even Heliocentrists admit that there is a limit to radar range based on factors such as frequency, power, atmospheric conditions etc.
However, if the Earth were curved, as you claim, radar wouldn't be able to travel as far as it does at sea, because the curve of the horizon would block the radar transmission. That the horizon does not block radar at such relatively short distances (e.g. 50km in the example I showed) is proof that the Earth is flat, not curved as you claim.