Illinois Superconductor Corp. said it has introduced an interference filter for cellular base station receivers that uses superconductor technology, enabling the base station to hear weaker signals more clearly.

Superconductivity involves cooling certain metals and alloys to a very low temperature so electrical currents can be transmitted without resistance. Illinois Superconductor’s filter rejects undesired radio signals, making the radio receiver’s sensitivity greater and allowing weak signals to be heard with greater clarity, according to the Evanston, Ill.-based company.

The technology is a spinoff from Argonne National Laboratory, and the filter is the first product of its kind to use superconductor experience in commercial technology, the company said. Even though Illinois Superconductor’s filter operates on the “high temperature” end of superconductivity, the product must still be cooled at lower than minus 300 degrees Fahrenheit. The company hopes to adapt the cryogenic refrigerator for commercial filter use, said Ora E. Smith, company president and chief executive officer.

“Government regulation in the wireless area has affected us positively because of the way cellular and other wireless spectrum has been allocated. The resulting spectrum congestion and interference has created a need for the high-performance products we’re developing,” Smith said.

As wireless communications gains popularity, radio systems are pressed closer together, physically and electrically, Smith said.

“This closeness has increased the interference experienced by mobile phone users and other wireless customers. These problems are widespread and are apparent in just about every cellular system in the world,” Smith said.

Two California companies are known to be developing a similar cellular filter, using a thin-film version of superconducting technology. Illinois Superconductor has applied for patents on a thick-film version, which is less expensive to manufacture, the company said.

Illinois Superconductor was founded in 1989 to commercialize superconductivity products for the wireless communications industry. In March of 1993, Illinois Superconductor signed U.S. government contracts valued at $745,000 for advanced technology programs. In June of 1993, the company signed a cooperative development agreement with AT&T Corp. The two companies are co-developing on a cost-sharing basis, Smith said.

Illinois Superconductor expects to start shipping filters this fall.

“The first-generation product will be designed for retrofit to existing analog stations and will also be useful in new analog and TDMA (Time Division Multiple Access) digital stations,” Smith said.

Operators using the filter can be more flexible in selecting cell sites, and the performance of handheld phones and other low-power, wireless instruments is improved because base station receiver sensitivity is increased, the company said.

The number of calls dropped due to interference can be reduced, and the filter allows for reduced guard band allocations, so carriers can maximize their frequencies, according to the company.

Illinois Superconductor’s second product group will be high-performance superconducting filters designed for Code Division Multiple Access digital cellular systems.

“Beyond that, we are co-developing with AT&T the technology for a new generation of cellular base station receivers, which will be much more complex systems that will use a large number of superconducting and cryo-electronic-cooled conventional electronic-subsystems,” Smith said.

Wireless products are the clear revenue winners for the company, he said.

“I think our business mix in cellular will be split about 50-50 between two classes of customers-cellular operating companies and the highly-concentrated set of turnkey system suppliers, like AT&T or Motorola (Inc.) We believe that business with cellular operators will be primarily a retrofit business, and that sales to turnkey suppliers will be mainly new systems,” Smith said.

Illinois Superconductor’s largest investors include the State of Illinois, Arch Development Corp., the University of Chicago, the Chicago-based venture capital firm of Batterson Johnson & Wang and Arch Venture Fund L.P .

Illinois Superconductor’s first initial public offering was completed last October, raising more than $15 million for the company. Total stockholders’ equity was $16.8 million at year’s end, according to the company’s 1993 annual report. The company suffered a net loss of $1.65 million last year.


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