In this paper, we start from the well known Durnin's experimental setup, finding general analytical formulae to investigate generation and propagation of nondiffracting beams. Our general formula makes possible considering any kind of angular modulation. As an example we discuss the Mathieu beams. Moreover, in the study of Bessel beams we consider the width of the slit to compare with the ideal case represented by a Dirac δ transmittance function. © 2003 Elsevier Science B.V. All rights reserved.