  We develop a generic all-inductive procedure to measure the band structure of
spin waves in a magnetic thin stripe. In contrast to existing techniques, our
method works even if several spin wave branches coexist in the investigated
frequency interval, provided that the branches possess sufficiently different
group velocities. We first measure the microwave scattering matrix of a network
composed of distant antennas inductively coupled to the spin wave bath of the
magnetic film. After a mathematical transformation to the time-domain to get
the transmission impulse response, the different spin wave branches are viewed
as wavepackets that reach successively the receiving antenna after different
travel times. In analogy with time-of flight spectroscopy, the wavepackets are
then separated by time-gating. The time-gated responses are used to recalculate
the contribution of each spin wave branch to the frequency domain scattering
matrix. The dispersion relation of each branch stems from the absolute phase of
the time-gated transmission parameter. The spin wave wavevector can be
determined unambiguously if the results for several propagation distances are
combined, so as to get the dispersion relations.
