Resumen
The structure has a passive filter (1) connected to an active interference stage (2). The active interference stage increases selectivity of the passive filter by generation of destructive interferences outside a passage band of the passive filter. Interference sections (4, 6) are separated by insulating stages (3, 5) consisting of communication lines that generate manifold zeros of transmission outside the passage band of the passive filter. A totally constructive interference is maintained in the passage band.