Smallest Nanoantennas for High-speed Data Networks
Nano dipole antennas under the microscope: The colors reflect the different trans-mission frequencies. (Photo by: LTI)
More than 120 years after the discovery of the electromagnetic character of radio waves by Heinrich Hertz, wireless data transmission dominates information technology. Higher and higher radio frequencies are applied to transmit more data within shorter periods of time. Some years ago, scientists found that light waves might also be used for radio transmission. So far, however, manufacture of the small antennas has required an enormous expenditure. KIT scientists have now succeeded for the first time in specifically and reproducibly manufacturing smallest optical nanoantennas from gold.
In 1887, Heinrich Hertz discovered the electromagnetic waves at the former Technical College of Karlsruhe, the predecessor of Universität Karlsruhe (TH). Specific and directed generation of electromagnetic radiation allows for the transmission of information from a place A to a remote location B. The key component in this transmission is a dipole antenna on the transmission side and on the reception side. Today, this technology is applied in many areas of everyday life, for instance, in mobile radio communication or satellite reception of broadcasting programs. Communication between the transmitter and receiver reaches highest efficiency, if the total length of the dipole antennas corresponds to about half of the wavelength of the electromagnetic wave. (more…)
Radio Waves ‘See’ Through Walls
Neal Patwari, a University of Utah assistant professor of electrical and computer engineering, works with doctoral student Joey Wilson. They have developed a system, using inexpensive radio transceivers like those on the table in front of them, for transmitting radio waves so that police, firefighters or other emergency personnel could "see" people moving behind walls, such as people held hostage or trapped by fire. (Jessica Croft, University of Utah)
University of Utah engineers showed that a wireless network of radio transmitters can track people moving behind solid walls. The system could help police, firefighters and others nab intruders, and rescue hostages, fire victims and elderly people who fall in their homes. It also might help retail marketing and border control.
“By showing the locations of people within a building during hostage situations, fires or other emergencies, radio tomography can help law enforcement and emergency responders to know where they should focus their attention,” Joey Wilson and Neal Patwari wrote in one of two new studies of the method.
Both researchers are in the university’s Department of Electrical and Computer Engineering – Patwari as an assistant professor and Wilson as a doctoral student.
Their method uses radio tomographic imaging (RTI), which can “see,” locate and track moving people or objects in an area surrounded by inexpensive radio transceivers that send and receive signals. People don’t need to wear radio-transmitting ID tags. (more…)
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