Abstract: A controllable switch matrix module is disclosed for bidirectional transmission of signals between multiple ports in a single module, where the attenuation characteristics are dynamically alterable. The invention uses pin diodes both for isolation and for switching, and achieves its high isolation in part by completely enclosing each of the attenuation functions within separate compartments, enclosing the connections between compartments for isolation between functions, and supplying control signals to the pin diodes using feedthrough connections designed in such a way as to prevent the emission of RF signals via the feedthrough devices. Only two bits are required to define any one of four attenuation levels between any two ports.