Which type of material or system performs similarly to resonant RADAR Absorbent Material (RAM) using a transmitter?

The correct answer highlights the role of Active Cancellation in the context of RADAR Absorbent Materials. Active Cancellation refers to systems that utilize electronic methods to neutralize incoming radar signals. This is achieved by transmitting a signal that is phase-aligned with the radar energy but has an opposite amplitude, effectively resulting in a destructive interference pattern that reduces the radar's ability to detect the target.

Resonant RAM is designed to absorb specific frequencies of radar energy effectively, using a physical material structure that resonates at those frequencies. Active Cancellation goes a step further by introducing a dynamic component — the transmitted signal — which can adapt to the frequency characteristics of the incoming radar waves in real-time. This means that the effectiveness of Active Cancellation can be higher than that of traditional absorptive materials since it can target and mitigate various radar frequencies actively.

Thus, although resonant RAM passively absorbs radar signals, Active Cancellation employs active electronic techniques that allow it to perform similarly by reducing radar detection capabilities dynamically. This makes it a sophisticated complement to traditional RAM approaches.