  There is a host of alternative theories of gravitation in the literature,
among them the $f(R,T)$ recently elaborated by Harko and collaborators. In
these theories the $R$ and $T$ are respectively the Ricci scalar and the trace
of the energy momentum tensor. There is already in literature a series of
studies of different forms of the $f(R,T)$ functions as well as their
cosmological consequences. However, there is not so far in the literature
studies related to the gravitational waves in $f(R,T)$ gravity. Here we
consider such an issue, in particular studying the putative extra polarization
models that can well appear in such theories. To do that, we consider different
functional forms for $f(R,T)$.
