Skip to main content

RF Shorts – June 16, 2011

Large Solar Flare Observed
A huge solar eruption last week raised concerns about potential problems to the power grid, satellites and other electronic systems. While the solar storm did not have a significant impact on Earth, several articles appeared with pictures of the storm and descriptions of what might have happened had it hit Earth.

The Christian Science Monitor article Solar storm delivers a glancing blow to Earth – and a warning by Mark Clayton states that "The solar storm caused by a massive eruption two days ago arrived at Earth Wednesday, but it was only a taste of what scientists say might come--and the world is not prepared."

In the article, John Kappenman, author of an Oak Ridge National Laboratory study on the potential impact suggested that rebuilding from a storm such as the Carrington event could take from four to 10 years.

"That's the fundamental difference between this threat scenario and the way we tend to learn from other disasters," said Kappenman. "This time we need to learn before it happens."

New Outdoor Wi-Fi Option Offered
Recently I reported on Towerstream's plans to provide high-speed Internet over Wi-Fi throughout seven square miles of Manhattan. described equipment from the Israel-based company Wavion that is designed to bring Gigabit capacity and 450 Mbps speeds to outdoor areas in the article Wavion Brings Wi-Fi to the Great Outdoors by Sarah Reedy. The article describes how the 802.11n base stations work in a harsh interference environment and can interface with wireless carrier's other services.

"The main challenge in the outdoors is interference, and Wavion gets around that by combining adaptive beam forming technology and Multiple Input Multiple Output (MIMO) technologies," said Reedy. "Its boxes also support SIM-based authentication for a seamless hand-off from the wireless network."

Printing Technique Speeds Metamaterials Production
MIT technology review describes A Practical Way to Make Invisibility Cloaks in an article by Katherine Bourzac.

According to Bourzac, "A new printing method makes it possible to produce large sheets of metamaterials, a new class of materials designed to interact with light in ways no natural materials can."

John Rogers, a professor of materials science and engineering at the University of Illinois at Urbana-Champaign, who developed the new printing method, said, "Everyone has, perhaps conveniently, been in the position of not being able to make enough [metamaterial] to do anything with it. We can now bang out gigantic sheets of this stuff."

Xiang Zhang, chair of mechanical engineering at the University of California, Berkeley, said, "Various metamaterials could be made bigger by this method. For example, macro scale 2D lenses and cloaks may be possible, and possibly solar concentrators, too."

Nicholas Fang, an associate professor of mechanical engineering at MIT, said, "This printing technique is quite powerful and has the potential to scale to very large areas."

Rogers' stamp-based printing method was demonstrated using near-infrared frequencies but could possibly be extended to cover radio frequencies. Metamaterials have been suggested as one way to reduce the size of antennas needed for VHF and UHF TV reception.

1.4 GHz Band Proposed for Easing Spectrum Shortage
A study by Plum Consulting Benefits of 1.4 GHz spectrum for multimedia services presented at the 6th Annual European Spectrum Management Conference in Brussels this week shows that "significant benefits could flow from use of 1.4 GHz band for a supplemental mobile downlink for enhanced multimedia and broadband services." The study was conducted jointly for Ericsson and Qualcomm. Wassim Chourbaji, senior director for government affairs at Qualcomm said, "while it might seem obvious to use the 1.4 GHz band as supplemental downlink, this has only become technologically possible with the development of HSPA+ and LTE-Advanced standards. The technology exists, the spectrum exists and the political will exists." He noted, however, that benefits from the use of this part of the spectrum would only be possible "if the band is harmonized in Europe and offers the economies of scale identified in the Plum Consulting study."

According to the study, the 1.4 GHz band is not available for supplemental downlink in the United States. However, Qualcomm and AT&T have been working to develop the Channel 55 MediaFLO spectrum for supplemental downlink, and Ericsson has shown how broadcast TV spectrum could be shared for this purpose by converting U.S. TV broadcasting to a cellular architecture using LTE and COFDM.

Doug Lung is one of America's foremost authorities on broadcast RF technology. He has been with NBC since 1985 and is currently vice president of broadcast technology for NBC/Telemundo stations.