A group of MIT researchers has developed a radar that provides a video of what is happening behind a concrete wall. Just like any other radar, the device emits radio waves that bounce off objects and analyzes the return signal. Dr. Gregory Charvat and his colleagues from MIT's Lincoln Laboratory estimate that penetrating an 8-inch thick concrete wall is possible from a maximum distance of approximately 60 feet (18,3 m). The 99.9975 percent of the signal that returns to the radar after bouncing off the wall is disregarded. The remaining part that made it through the wall and back is amplified and used to generate a real-time, 10.8 frames per second visualization of the targets on the other side.
Read the full article: MIT-developed radar sees through concrete walls up to eight inches thick