  We have measured antiferromagnetic resonance (AFMR) frequency-field
dependences for aluminum-manganese garnet Mn$_{3}$Al$_{2}$Ge$_{3}$O$_{12}$ at
frequencies from 1 to 125 GHz and at the fields up to 60 kOe. Three AFMR modes
were observed for all orientations, their zero field gaps are about 40 and 70
GHz. Andreev-Marchenko hydrodynamic theory [Sov. Phys. Usp. 130, 39 (1980)]
well describes experimental frequency-field dependences. We have observed
hysteresis of resonance absorption as well as history dependence of resonance
absorption near gap frequencies below 10 kOe in all three measured field
orientations, which are supposedly due to the sample domain structure.
Observation of the AFMR signal at the frequencies from 1 to 5 GHz allows to
estimate repulsion of nuclear and electron modes of spin precession in the
vicinity of spin-reorientation transition at H||[100].
