EN
We discuss the applied magnetic field dependence of the microwave absorption by a three-dimensional array of up to 30×30 ×30 Josephson junctions with random parameters including the resistivity, capacity, and inductance of each junction. The numerical simulation results for the networks show characteristic microwave absorption anomalies observed in the ceramic samples of high temperature superconductor YBa_2Cu_3O_{7-x}. We also provide a discussion of the absorption in simple analytical terms of the Josephson loop instabilities.