  In this paper we investigate Ramanujan hypergraphs by using hypergraph
coverings. We first show that the spectrum of a $k$-fold covering $\bar{H}$ of
a connected hypergraph $H$ contains the spectrum of $H$, and that it is the
union of the spectrum of $H$ and the spectrum of an incidence-signed hypergraph
with $H$ as underlying hypergraph if $k=2$, which generalizes Bilu-Linial
result on graph coverings. We give a lower bound for the second largest
eigenvalue of a $d$-regular hypergraph by universal cover, which generalizes
Alon-Boppana bound on $d$-regular graphs and Feng-Li bound on $(d,r)$-regular
hypergraphs. By using interlacing family of polynomials, we prove that every
$(d,r)$-regular hypergraph has a right-sided Ramanujan $2$-covering, and has a
left-sided Ramanujan $2$-covering if the roots of the matching polynomial of
its incident graph satisfy some condition. By Ramanujan $2$-coverings, we prove
the existence of some families of infinite many left-sided or right-sided
$(d,r)$-regular Ramanujan hypergraphs under certain conditions on $d$ and $r$.
