It's happened to all of us. You're on your cell phone, your boss is saying something important, and then the connection starts to drop out. Now a team of physicists in Denmark, led by Albert and Eugene Polzik, has demonstrated a new kind of radio tuner that is far more sensitive to faint signals. The technique could eventually mean fewer dropped calls, better GPS coverage, faster Wifi, and much more detailed images from MRI scanners. The tuner includes a novel component: a tiny reflective membrane just half a on a side and only a hundred nanometers thick. It functions in the circuit as a capacitor, and when radio waves pass through the antenna, the voltage shifts make the membrane bounce like a trampoline. Laser light, off the membrane and then interfering with itself, turns those nanometer-high wiggles into a strong, clear signal. The report is on the site arXiv.org. The scientists are excited about how the technology might sharpen the pictures produced by radio . But wouldn't it also be nice to get decent phone reception inside a parking garage?