– This paper presents the realization of the digital block of a hardware simulator of MIMO propagation channels for UMTS and WLAN applications. The hardware simulator must reproduce the behavior of the radio propagation channel, thus making it possible to test “on table” the mobile radio equipments. The advantages are: low cost, short test duration, possibility to ensure the same test conditions in order to compare the performance of various equipments. After the presentation of the general characteristics of the hardware simulator, an architecture of the digital block is proposed and its accuracy is analyzed.