"Is it operating within the realm of physical sciences and spectrum that we all know and accept? Yes," Schober said. Beyond that, there's not much. "We're not focusing on what's traditionally called radio frequencies," he said.
If the Manta Ray is just a non-transmitting, passive sensor, there's not much for it to sense, said Farpoint Group analyst Craig Mathias, a longtime student of many wireless technologies.
"A cellphone that is completely off emits no radiation that I'm aware of," Mathias said. He suggested it might use magnetism.
"I'm sure it's not magic, I'm sure it works," Mathias said. "But it's weird."