  Recently we have studied in great detail a model of Hybrid Natural Inflation
(HNI) by constructing two simple effective field theories. These two versions
of the model allow inflationary energy scales as small as the electroweak scale
in one of them or as large as the Grand Unification scale in the other,
therefore covering the whole range of possible energy scales. In any case the
inflationary sector of the model is of the form $V(\phi)=V_0 \left(1+a
\cos(\phi/f)\right)$ where $0\leq a<1$ and the end of inflation is triggered by
an independent waterfall field. One interesting characteristic of this model is
that the slow-roll parameter $\epsilon(\phi)$ is a non-monotonic function of
$\phi$ presenting a {\it maximum} close to the inflection point of the
potential. Because the scalar spectrum $\mathcal{P}_s(k)$ of density
fluctuations when written in terms of the potential is inversely proportional
to $\epsilon(\phi)$ we find that $\mathcal{P}_s(k)$ presents a {\it minimum} at
$\phi_{min}$. The origin of the HNI potential can be traced to a symmetry
breaking phenomenon occurring at some energy scale $f$ which gives rise to a
(massless) Goldstone boson. Non-perturbative physics at some temperature $T<f$
might occur which provides a potential (and a small mass) to the originally
massless boson to become the inflaton (a pseudo-Nambu-Goldstone boson). Thus
the inflaton energy scale $\Delta$ is bounded by the symmetry breaking scale,
$\Delta\equiv V_H^{1/4} <f.$ To have such a well defined origin and hierarchy
of scales in inflationary models is not common. We use this property of HNI to
determine bounds for the inflationary energy scale $\Delta$ and for the
tensor-to-scalar ratio $r$.
