Landsat doesn't have a radar sensor. Google Scholar is your friend: https://scholar.google.com/scholar?hl=en&as_sdt=0,48&q=Satellite+SAR+archaeology

Are you trying to 'discover' a new site, or replicate / extend an existing discovery? There are quite a variety of platforms, sensors, and beam modes, so one needs some idea of what features and their signatures you are trying to detect. NASA and ESA have data portals to find imagery.