Mastering spin waves interference at the sub-micron scale is central for the development of wave-based computing applications such as reservoir computing [1], holographic memory [2], or spectral analysis [3]. The complexity of spin dynamics, inherently due to its dependence to numerous parameters, and also to the intricacy of magnon-magnon interactions, requires heavy computational methods, which can limit the scope of study. In this context, we developed an efficient tool to study the near-field diffraction (NFD) patterns of spin wave in homogeneous out-of-plane magnetized thin films for arbitrary distribution of excitation field [4]. In this communication, we extend our NFD model to in-plane magnetized films, taking into account the coupling between higher order standing spin-wave modes in order to recover the thickness dependence of the interference patterns. We show in particular how caustic beams can be directly emitted from a sharply constricted stripline (see Fig. 1). This model allows to explore efficiently magnon beamforming over the wide range of parameters such as field, frequency, magnetic properties, shape and scale of antennas.