Microwave Engineering Europe - May 2008 - (Page 17)

WIRELESS NETWORKING — INDOOR SOLUTIONS 17 itself — narrow and conﬁned or open-plan expanse — is inﬂuential. Managing interference with other interior applications is another key consideration — but especially with security sensitive equipment or medical devices. Of course, interference can originate from outside also — such as WiMAX at 2.5 GHz interfering with WiFi indoors, or WiFi networks being hacked into from external buildings. All such interference and security issues can be overcome or managed. Already endeavouring to match the demands of existing technology, the industry is becoming cognizant of the necessity for future-prooﬁng as emergent technologies gain strength and favour. Higher-frequency services — UMTS and WiMAX, for example — may exhibit poor building penetration, but will likely meet strong consumer acceptance once they are widely deployed. For property developers, owners and managers, the availability of such services will be an increasingly attractive selling point to prospective purchasers, investors and tenants. Moreover, the type of solution — or system architecture — is selected based on that which will provide the optimum return on investment (ROI). The strong current wireless indoor market is expected to be even more poweredup in years to come, and traditional and new market offerings (both licensed and unlicensed) converge. New business models pushed by managed communications services offerings, and new free ‘skype-like’ approaches, will propel the indoor market to centre-stage, strategically and economically. Figure 4: WINS infrastructure founded on radiating cable provides contoured coverage for WiFi. Waveguides bridge ‘terahertz gap’ Wires that carry terahertz electromagnetic radiation could carry 1,000-GHz signals. Until now, the terahertz gap has prevented circuitry from rising much above 60 GHz—the speed of next-generation wide personal-area networks. Recently, researchers at the University of Utah have demonstrated a method of building wires that act as terahertz-caliber waveguides atop stainless-steel foil by using lines of micron-scale perforations. The technique was shown to transmit, bend, split and combine terahertz radiation at 0.3 THz (300 GHz) but could be extended up to 10 THz, according to electrical-engineering professor Ajay Nahata at the university. Terahertz frequencies exist in the gap between microwaves and the infrared wavelengths used by optical ﬁbers. Terahertz electromagnetic signals have properties of both electrical signals and optical signals, requiring waveguide-like structures, but in a form factor similar to the wiring used by an electrical signal. Nahata has now demonstrated a wiring method that focuses radiation into a perforated metallic “wire” that acts like the splitter used to feed a cable-TV signal to two televisions, an essential element of future terahertz circuitry. Nahata estimates that within 10 years, his demonstration will lead the way to terahertz-speed circuitry for computers and communications. The University of Utah demonstration builds on the theoretical results of Stefan Maier, a researcher at Imperial College (London), who collaborated with scientists at the University of Bath, the University of Madrid and the University of Zaragoza, Spain. Maier and colleagues demonstrated earlier this year that surface plasmon polaritons — electromagnetic surface waves supported at the interface between a metal and a dielectric (copper and a polymer) — could guide terahertz signals. Nahata and his colleagues at the University of Utah fabricated their waveguide and signal splitter using steel as the conductor and air as the dielectric, by virtue of perforating a stainless-steel foil with rectangular holes measuring 50 x 500 microns. The waveguide was about an inch long and the foil about 625 microns thick. The researchers say they have shown that the grooves enabled 0.3-THz radiation to be focused into the waveguide, where it traveled to within 1.7 mm of the foil’s surface, spreading horizontally only about 2 mm as it followed the pattern of perforations. www.mwee.com/207401447 Microwave Engineering ● May 2008 ● www.mwee.com http://www.mwee.com/207401447 http://www.mwee.com

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Microwave Engineering Europe - May 2008 News Contents Comment Cover Feature: How to Succeed as a GaAs Foundry Wireless Networking: Wireless Coverage Where Everybody WINS Wireless Networking: Achieving Good Coexistence in the 2.4 GHz ISM Band GPS and Satellite: GPS developments: Galileo Moves Forward with Successful Giove-B Satellite Launch — Broadcom Targets AGPS in Mobile Phones and Devices Raising the Bar for the Radio: Making 802.11n Work Reducing Power Consumption in Ultrawideband Chips WiMax Catches Second Test Wave Products Calendar

Microwave Engineering Europe - May 2008

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