Millimeter-Wave Systems for Wireless Communications

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9979296DelisioOur society has experienced unprecedented growth in the exchange of information over wireless communication networks. This decade alone has witnessed an explosion in the use of electronic mail, the World Wide Web, cellular telephony, mobile computing, electronic pagers, and video conferencing. These services will undoubtedly become even more popular as we enter the 21St century, but today's wireless communication networks will soon be unable to handle the inflated bandwidth requirements for these and future interactive, broadband, multimedia services.The millimeter-wave band (30 - 300 GHz) clearly offers the spectrum to accommodate broadband, high-speed services. Achievable transmission rates are on the order of 5 Gbps -- more than 100 times the T3 (45 Mbps) transmission rate. In fact, this rate is competitive with that of optical fiber, which is currently the technology of choice to transmit large amounts of information. Millimeter-wave networks not only provide the necessary bandwidth for high bit rates and wide-band modulation schemes, but the associated short wavelengths also imply smaller antenna and circuit size, resulting in more compact modules for mobile communications. The increased atmospheric attenuation in this part of the spectrum is useful for secure satellite cross-links and high-capacity wireless local-area networks.In some nations the development of these systems is already well underway. For example, Japan has developed 60-GHz, 155-Mbps wireless local area networks for multimedia distribution. If the United States is to preserve its role as the world's leader in high-speed communications, it must act quickly. The Federal Communications Commission has considered frequency allocations as high as 150 GHz.Realizing communication components at millimeter wavelengths, however, presents a number of technical challenges in devices, circuits, coding, signal processing, and networks. At the University of Hawaii, faculty members of the College of Engineering have formed a strong team to focus on wireless technology in each of these areas. This proposal describes the device, circuit, and subsystem issues. A companion proposal describes the signal processing and networking issues.This research could enable an entirely new generation of millimeter-wave components for wireless communication. Improved passivation techniques promise electronic devices with low noise, high reliability, and high breakdown voltages. Revolutionary MEMS devices allow greater functionality and superior performance. The quasi-optical reflection amplifiers could be used in powerful solid-state transmitters. Quasi-optical diode and active mixers would be integral components in sensitive mixers with the dynamic range necessary for high-performance applications. Quasi-optical subsystems incorporating MEMS reconfigurable antennas and photonic crystals hold great promise. Possible communication applications include high-speed mobile personal communication systems, wireless local area networks, and emergency relief communications transceivers. Fueled by the demand for faster and faster data rates, these communication applications will continue to evolve toward millimeter-wave frequencies.***