The lumber and chicken-wire antenna on the roof of Gary Noreen's car drew a lot of attention on southern California freeways last fall. With $5,000 worth of radio equipment, Noreen demonstrated that a vehicle in any part of the country -- on a crowded city expressway or a deserted backwoods road -- could communicate via satellite. Now Noreen is working with Federal Express Corp. to test the new service.

Noreen's company, Transit Communications Inc., of Pasadena, Calif., is among a handful of companies jockeying for position in land-mobile satellite service (LMSS), an industry that is still unborn. The Federal Communications Commission is holding hearings on LMSS and will decide this spring what frequencies, if any, to allocate to LMSS. Probably no more than two companies can be expected to receive licenses to operate systems, says Jerry Freibaum, chief of technical consultation services at the National Aeronautics and Space Administration, which allowed two old satellites to be used for hundreds of experiments over the past 10 to 15 years. Most notably, an LMSS hookup maintained contact with rescue teams at the volcanic eruption of Mount St. Helens, in Washington State.

Transit Communications may not be among the fortunate licensees. Skylink Corp. and Mobile Satellite Corp. already have financial plans that will assure them of funding once FCC licensing is granted. Skylink hopes to launch a mobile satellite-phone service for air, land, and sea communications, while Mobile wants to use LMSS to provide mobile radio-telephone service to nonurban areas.

Noreen, 31, formerly at the California Institute of Technology Jet Propulsion Laboratory, has worked as a consultant to Federal Express, helping the company to prepare its applications for LMSS experiments. Federal Express is interested in using the technology to communicate with its fleet in remote locations. Noreen hopes that his association with federal Express will put him in a good position once licenses are granted.

However, he as well as his competitors are keenly aware of the risks. John Kiesling, president of Mobile, says, "Unless we are chosen as a system operator, we have nothing."