While many web sites have stories on the new "spray-on antenna", I've been able to find little detail on how they actually work. Engadget's James Trew has good coverage and a video of the basic idea in his article Spray-on antenna revealed: best thing to come in a can since Easy Cheese. The product was described at Google's first Solve for X gathering. It was developed by start-up Chamtech, whose CTO Rhett Spencer claims the antenna "can increase mobile energy efficiency by 10 percent." The ChamTech web site has little information, but the ChamTech Operations Spray On Antenna Kit web page shows two spray cans, a length of coax, some short adapter cables with RF connectors, an instruction book and some other items I couldn't identify. The project is targeted at military operations and my guess is it that its primary use would not be at "Wi-Fi" frequencies but at lower frequencies, longer wavelengths (VHF and HF), where a larger antenna is needed for efficient operation. It can be sprayed on buildings, trees and even used underwater!
The spray on antenna described above is interesting but the liquid crystal antenna designed by doctoral candidate Onur Hamza Karabey at the Technische Universität Darmstadt seems more likely to see eventual use in consumer products. The antenna uses a liquid crystal matrix designed by Karabey in collaboration with Professors Dr. Rolf Jakoby and Dr. Felix Goelden. Voltages applied to the matrix delay the incidence of radiowaves on the antenna. Changing the voltage changes the delay of the liquid crystal antenna elements, which, the Technische Universität Darmstadt news release says "allows amplifying radiofrequency signals coming from a particular direction and enables the matrix to virtually collect the radiofrequency irradiation incident on its entire surface area."
Karabey said, "Our objective is developing an ultralow-cost, phased-array antenna whose performance will be adequate for satellite reception." The antennas could be manufactured in the same manner as LCD screens and it is expected they would sell for less than 600 Euros. They have no moving parts, can be aligned on satellites within milliseconds, and are only about 5mm thick. Rolf Jakoby added, "Such antennae may even be partially transparent, which gives product designers considerable leeway in meeting buyers' needs."