Can radio waves be polarized

Yes, like all electromagnetic radiation can be polarized.

The A. T. & T. Long Lines Microwave tower system doubled its long distance call capacity by using cross polarized microwaves. This system operated from the late 1940s to the early 1990s (when fibre optics superceded it, but many of the towers and horns remain, see the image above showing a transmitting/receiving pair of horns).