|  Let  be real numbers such that  and let  a mixed homogeneous function. We consider polynomial functions  and also functions of the type  Let  with the Lebesgue induced measure. For  and  let  where  denotes the usual Fourier transform.  For a large class of functions  and for  we characterize, up to endpoints, the pairs  such that  is a bounded operator from  on  We also give some sharp  estimates.; |