We present several approaches that allows exciting non-reciprocal spin wave beams in thin magnetic films such as curvilinear antennas, grating of nanomagnets, and sharp constrictions. We first present a near-field diffraction model that benchmarks spin wave beamforming in thin films for any geometry. Then, we experimentally test our predictions using both spin wave spectroscopy and micro-focused Brillouin light spectroscopy to map diffraction patterns in the 2D plane. We will show in particular how a sharp constriction in an antenna can directly excite non-reciprocal caustic beams in an extended film when the suitable conditions of field and frequency meets an inflection point in the dispersion relation. These findings have important implications for the development of switchable spin wave splitters, passive spin-wave frequency-division demultiplexers, and magnonic interferometry.