As Bill Johnson has observed, rather more diplomatically than some people might haveThe answer is "not really, except in the answersense that currentlyCarlo Beenaker has been given (at time of writing) is grievously mistakenmentioned".
I would advise both the original questioner, and the author of the answer, tosuggest you look at the discussion of the Hausdorff–Young inequality in Chapter IV Section 2 of Katznelson's Introduction to Harmonic Analysis (2nd edition, Dover). Probably there will also be the same cautionary remarks and salutary counterexamples in Edwards's book Fourier Series.
(Could someone please do me the favour of flagging this as CW?)