Extensions of the Heisenberg group by two-parameter groups of dilations

We introduce extensions of the multidimensional Heisenberg group ${\mathbb{H}}^n$ by two-parameter groups of dilations, and then classify the extended groups up to isomorphism, by employing Lie algebra techniques. We show that the groups are isomorphic to subgroups of the symplectic group $\mathit{\text{Sp(}}n+1,\mathbb{R})$ as well as subgroups of the affine group $\mathit{\text{Aff}}(n+1,\mathbb{R})$. Thus, they possess both, a metaplectic and a wavelet representation. Moreover, the metaplectic representation splits into a sum of two subrepresentations which both are equivalent to the same subrepresentation of the wavelet representation.