Researchers at Fractal Antenna Systems have produced an antenna with a wideband microwave invisibility cloak. However, you can still see the antenna with your eyes, as its unique properties occur at microwave frequencies, well below the visible spectrum.
"In 2008, Chinese researchers said it was impossible to make a wideband invisibility cloak," writes Nathan Cohen, Fractal Antenna's CEO and chief inventor. "We not only did it, but reduced the number of cloak layers, and, most importantly, made a cloak you can see out of. That means a sensor, for example, can be made to disappear into the background over a wideband, but still be able to see what's outside. These attributes are really the 'holy grail' of cloak designs, and strongly point towards a bright future for invisibility science."
Cohen added that his involvement in amateur radio was a factor in developing the device.
"I have a Ph.D. in astrophysics and am a retired college professor," he said. "But the experience I gained as a young ham radio operator was invaluable in helping me make knowledge connections to make the cloak work. That's, in part, why my research group did this first, and why we continue to lead in innovation in fractal electronics, both in basic research and application to products."
Here's a video showing the antenna and how it works. Additional information used in this article is from Nanotechwire.com.