In this paper we derive L p − L q estimates, with 1 ≤ p ≤ q ≤ ∞ (including endpoint estimates asfor a general class of dissipation terms, where Af = F −1 (a(ξ) F f (ξ)), with a ∈ C n+1 (R n \ {0}), and a(ξ) > 0 verifies conditions of Mikhlin-Hörmander type for M q p multipliers which may be different at low frequencies and at high frequencies; in particular a(ξ) may also be inhomogeneous and anisotropic. We prove that the obtained estimates are sharp.
Key words and phrases. Dissipative wave equations, L p − L q estimates, M q p multipliers, decay estimates, non-effective damping.