The novel antennas may be useful in ever-shrinking and proliferating wireless systems such as emergency communications devices, micro-sensors and portable ground-penetrating radars to search for tunnels, caverns and other geophysical features.
NIST engineers are working with scientists from the University of Arizona (Tucson) and Boeing Research & Technology (Seattle, Wash.) to design antennas incorporating metamaterials—materials engineered with novel, often microscopic, structures to produce unusual properties. The new antennas radiate as much as 95 percent of an input radio signal and yet defy normal design parameters. Standard antennas need to be at least half the size of the signal wavelength to operate efficiently; at 300 MHz, for instance, an antenna would need to be half a meter long. The experimental antennas are as small as one-fiftieth of a wavelength and could shrink further.
In their latest prototype device,* the research team used a metal wire antenna printed on a small square of copper measuring less than 65 millimeters on a side. The antenna is wired to a signal source. Mounted on the back of the square is a “Z element” that acts as a metamaterial—a Z-shaped strip of copper with an inductor (a device that stores energy magnetically) in the center (see photo).
“The purpose of an antenna is to launch energy into free space,” explains NIST engineer Christopher Holloway, “But the problem with antennas that are very small compared to the wavelength is that most of the signal just gets reflected back to the source. The metamaterial makes the antenna behave as if it were much larger than it really is, because the antenna structure stores energy and re-radiates it.” Conventional antenna designs, Holloway says, achieve a similar effect by adding bulky “matching network” components to boost efficiency, but the metamaterial system can be made much smaller. Even more intriguing, Holloway says, “these metamaterials are much more ‘frequency agile.’ It’s possible we could tune them to work at any frequency we want, on the fly,” to a degree not possible with conventional designs.
The Z antennas were designed at the University of Arizona and fabricated and partially measured at Boeing Research & Technology. The power efficiency measurements were carried out at NIST laboratories in Boulder, Colo. The ongoing research is sponsored by the Defense Advanced Research Projects Agency.
* R.W. Ziolkowski, P. Jin, J.A. Nielsen, M.H. Tanielian and C.L. Holloway. Design and experimental verification of Z antennas at UHF frequencies. IEEE Antennas Wireless Propag. Lett., 2009 vol. 8, pp. 1329-1332
Laura Ost | Newswise Science News
Did you know that the wrapping of Easter eggs benefits from specialty light sources?
13.04.2017 | Heraeus Noblelight GmbH
To e-, or not to e-, the question for the exotic 'Si-III' phase of silicon
05.04.2017 | Carnegie Institution for Science
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
24.04.2017 | Physics and Astronomy
24.04.2017 | Materials Sciences
24.04.2017 | Life Sciences