We have investigated the electrodynamic response of UPd2Al3 both above and below the antiferromagnetic phase transition at TN = 14 K. At low temperatures, we observe the formation of a low-frequency narrow resonance, which indicates the development of the many-body coherent state. However, we do not fmd any evidence of a gap absorption associated with a spin-density-wave state, which would develop if the state arised as a consequence of a Fermi surface instability
