Résumé
We consider the production of chargino and charged Higgs boson pairs at future linear colliders for c.m. energies in the one TeV range. Working in the MSSM under the assumption of a "moderately" light SUSY scenario, we compute the leading (double) and next-to leading (linear) supersymmetric logarithmic terms of the so-called "Sudakov expansion" at one loop. We show that a combined analysis of the slopes of the chargino and of the charged Higgs production cross sections would offer a simple possibility for determining $\tan\beta$ for large ($\gtrsim 10$) values and an allowed strip in the ($M_2,\mu$) plane. This could provide a strong consistency test of the considered supersymmetric model.