>>8936105 (lb)
it's used in many places in communications & optics
in your example they are using it to help prevent interference from adjacent channels
a circular polarized signal will experience less interference from adjacent linear polarized channels
IF you really want to know and understand this topic I'd be happy to oblige somewhere else and explain what I know and point to you to good reference material to explain it fully
HERE this is a slide topic and not truly relevant to theQ