An analysis is made of two methods of predicting the far‐field radiation pattern from pressure measurements made over a closed surfaceS, containing the source. One of these methods involves the use of Green's functions and yields two subcases according to the particular Green's function that is used. The Helmholtz formula, which results when one uses a Green's function of the form exp(ikR)/R, requires the knowledge of the normal gradient of the pressure ∂p/∂noverSin addition to the pressurep, but it leads to a formula that is relatively easy to evaluate. An approximation to ∂p/∂nis discussed. If, instead, one uses the Green's function which vanishes over the surfaceS, one can evaluate the pressure in the far field, in terms of measurements overS, ofponly. The resulting formula is somewhat more complicated than the Helmholtz formula, but it does not require a knowledge of ∂p/∂n.The second method is based on a proposal recently made by Pachner. It is shown, for the case of prolate spheroidal coordinates, that Pachner's method is completely equivalent to the second approach mentioned above. The applicability of these formulas is demonstrated with experimental data for a line hydrophone. Good agreement is obtained between the experimental radiation pattern and the theoretical patterns predicted by the formulas.