Radar vision

For a long time, characters in science fiction films and comic books could see through walls. Superman's X-ray vision allowed him to see invisible dangers and catch hidden villains. It's a gift that many police officers and firefighters wish they could apply in the real world.

Now it looks like help is on its way. Researchers at Ilmenau University of Technology have developed an ultra-wideband (UWB) radar antenna that can be used to literally see through walls.

The antennas consist of three hand-sized metal cones, placed horizontally with the opening directed at the wall.

"We use them to transmit electromagnetic waves," researcher Rudolf Zetik said. "If these waves contain low frequencies, they can easily pass through walls. Then, for instance, they can bounce off a person, who reflects them."

Turning waves into information

Using a receiver, the researchers can capture the reflected waves and transmit them to a computer, whose monitor shows what looks like what we normally get when there's no TV signal. But if a person moves behind the wall, a wave pattern is created and it becomes thicker, wider and even changes color.

The waves also relay information on whether someone is standing behind the wall, whether he is breathing and how strong his heartbeat is. "That means that we would be able to detect unconscious people after an earthquake," Zetik said.

To the inexperienced, the information on the screen isn't particularly clear, but Zetik can tell how far away the person is standing and whether he is moving toward or away from the wall. An additional antenna, attached to another wall, can help the researchers locate a person within the room more accurately.

"If the sensors are spread out, you get a better idea of what's inside," explained Zetik's colleague Snezhana Jovanoska. The system can also recognize in what direction people are going. "For instance, you can also see where the firefighters are in a building, and if they are in danger," Jovanoska said.

The researchers say the radar could also be used to help the police see what is happening in a hostage situation - for instance, to see how far the victims are from the hostage-taker, and whether he is calm or moving around frantically.

The system interface is designed to be as easy-to-use as possible, because precise information is needed quickly in an emergency situation. That means the data from the wave pattern has to be converted to a format that is easy to understand. "We only show the required information on the interface," Zetik said. Green dots, for instance, are used to represent humans.

Test phase

Zetik added that the system can also be set to show how fast or slow someone is breathing, and determine their physical condition.

The researchers have already begun carrying out tests to show how the system would work in a real-life emergency operation. In one of these, Zetik and his team re-created a post-earthquake scenario. A woman was buried under several meters of rubble and debris made up of different materials. Apart from breathing, she did not move. "We could locate exactly where she was in the rubble," Jovanoska announced.

But the radar is yet to be used in an actual emergency. This could soon change, since the Fraunhofer Institute for Communication, Information Processing and Ergonomics is helping the researchers turn their idea into a finished product.