To provide cellular phone or PCS service, a communications company using a land-based approach must place base stations - towers and reception/transmission equipment - at regular intervals throughout its service area. In deciding where to locate these base stations, the company considers the strength and clarity of its communications signals and how customer service will be affected when a signal shifts from one station to the next while the customer is traveling.

All these factors depend on how well the station's equipment handles the communications signals. And that depends on how well each component of the equipment works as it attempts to distinguish the user's cellular phone signal from the surrounding electronic noise.

A High-Temperature Superconductivity Solution

This ATP project with Illinois Superconductor Corporation (ISC), a small company founded in 1990, developed technology based on high-temperature superconductivity (a phenomenon discovered in 1986) to significantly improve the quality of signal transmission.

Superconducting components offer great benefits to cellular phone communications, including improvements in range, receiver sensitivity and frequency stability. These improvements, in turn, will extend the range of base stations, reducing the number needed to cover a given area and decreasing the costs of cellular phone service. Cellular phone users will receive clearer signals and suffer fewer dropped calls as their signals move from one base station site to the next.

Despite the promise of superconducting components, little prior work had gone into developing HTS components for the radio-frequency (RF) spectrum, which is used by cellular phone systems. Difficulties in economically making the relatively large, geometrically complex structures needed for these frequencies were partly to blame. ISC solved this problem by developing the ability to use thick-film HTS coatings on inexpensive substrates.

Focus on Preselector Receive Filters

The goal of the ATP project was to develop and demonstrate consistently performing RF superconducting components in a prototype base station. During the ATP project, however, ISC narrowed its focus (with ATP approval) to preselector receive filters, which remove all extraneous RF signals and leave only those within the cellular spectrum allotted to that particular operator. Investigation of the cellular market indicated that the superconducting preselector receive filter was of greatest interest to customers in terms of improving system performance. Given the limited resources available to ISC, the company decided to focus on this component as an initial goal and to integrate others later. The new HTS technology is useful for other RF equipment and has potential applications in antennas, magnetic resonance imaging machines and other components of communications systems.

ISC successfully incorporated the ATP-funded technology in a preselector receive filter and, in late 1996, started selling it under the name of SpectrumMaster(r) to companies operating cellular phone systems. A year later, it launched RangeMaster(r), which contains the SpectrumMaster(r) preselector receive filter and a cryogenically cooled low-noise amplifier. By September 1997, ISC had installed SpectrumMaster(r) or RangeMaster(r) in 22 base stations in 12 cities and had successfully completed 16 field trials in 10 cities. Sales at that time amounted to $1 million. The company has also modified and installed SpectrumMaster(r) for use in the base stations of personal communications systems.

Improved Communications Service

The future looks bright for ISC as it uses the ATP-funded technology to help communications companies serve their customers with greater-quality services at lower costs. Cellular phone service companies can reduce the number of new base station sites they install. They can also expand by up to 25 percent the range of existing sites by replacing an older filter at the station with a new one based on the ATP-funded technology. A 25 percent range increase corresponds to a 56 percent increase in the area covered and translates into a 40 percent decrease in the number of sites required to cover the area. The cost of the improved filter is around $25,000 to $60,000, depending on site configuration, whereas the cost of a new site is about $1 million to $2 million.

The future also looks bright for customers of these communications companies, as costs drop and service quality improves.

Even greater benefits should accrue to cellular and personal communications customers with the conversion from analog to digital communications. Digital stations must transmit much more data per call, so any quality improvements or cost reductions will apply to a larger volume of signal traffic. As more transmission sites install digital systems, cellular phone users will get clearer signals and fewer dropped calls. Other sectors, such as mobile communications, will experience lower costs and improved quality as the technology is extended to them. Proliferation of the new technology will provide an additional benefit in terms of aesthetics by reducing the number of signal towers installed for communications systems.

ATP Award Accelerates Development

Funding from the ATP enabled ISC to form alliances with research partners and contractors and to achieve its research and development results about 18 months earlier than it would otherwise have been able to do. Company officials say the ATP award also enabled ISC to survive as a company and gave its technology and commercialization plan significant credibility with investors. The increased credibility, in turn, directly helped the company raise private capital, especially during its initial public stock offering in 1993.

Go to other sections of Chapter 5: ELECTRONICS
	Expanding the Number of Light Signals in an Optical Fiber
	Manufacturing Technology for High-Performance Optoelectronic Devices
	Processes for Growing Large, Single Silicon Carbide Crystals
	Harnessing Cheap Diode Lasers to Power a Low-Cost Surgical Laser
	Lowering the Cost and Improving the Quality of Computer Chips
	A Gas Method to "Dry" Clean Computer-Chip Wafers
	Low-Cost Night-Vision Technology
	Large-Scale Diode-Array Laser Technology for X-Ray Lithography
	Using High-Temperature Superconductivity to Improve Cellular Phone Transmission
	Exploiting Alexandrite's Unique Properties for a Less-Expensive, More-Reliable Tunable Laser
	Precision Mirrors for Advanced Lithography
	Joining Several Chips Into One Complex Integrated Circuit
	Computer RAM Chips That Hold Memory When Power Is Off
	A Feedback-Controlled, Metallo-Organic Chemical Vapor Deposition Reactor
	Flat Fluorescent Lamps for Displays