A plan to create 700 new AM radio stations in the United States has run into trouble at the world radio conference in Geneva.

A majority of the Western Hemisphere nations attending the conference oppose the U.S. expansion plan because they fear it will interfere with their own domestic communications systems.

The U.S. proposal, which would have the International Telecommunications Union approve the expansion of the frequency band allocated to AM broadcast, has the support of the Federal Communications Commission, which sees it as a vehicle to advance minority ownership in broadcast properties.

But other countries in this hemisphere are opposing the plan because they already use the portion of the band that would be allocated to the new AM stations for other services such as amateur radio broadcasting.

A second U.S. proposal, which would have solar energy beamed to the earth from a satellite orbiting the globe has also met resistance at the World Administrative Radio Conference (WARC), now in its ninth week in Geneva.

The solar proposal has raised the interest of several of the 150 nations in attendence at the conference, which meets once every 20 years to divide up the world's airwaves.

Many of those countries have expressed concern that the transmission of power from outer space could have harmful effects.

The satellite, called the Solar Power Satellite, would convert sunlight into 5-billion-watt to 10-billion-watt microwave beams directed to giant antennas in the United States.

The system uses a vast, 20-square-mile platform of solar cells orbiting some 22,000 miles out in space to gather the sun's rays.

The rays are then converted to electricity and beamed as a microwave to the earth and fed into the U.S. national power grid.

Sponsored by the Department of Energy, the National Aeronautics and Space Administration and several private aerospace industry contractors, the project was offered as one of hundreds of U.S. proposals at WARC.

The problems with the proposal are twofold. First, several countries feel that too much space on the radio band has been requested for the service, proposing instead to devote only half of the 100 megahertz spectrum requested by the U.S. to the service.

The second problem, raised by several delegates with scientific and engineering backgrounds, involves the possibility that the service could interfere with other services, and may have environmental or health side effects.

So despite considerable interest in the project, largely because of its power-generation abilities, it appears that the project may have difficulty getting off the ground. Proponents say that only if the SPS is approved this year, could it be fully operational by the end of the century.

Final votes on both proposals will come at the end of the conference next week.

The conference has been largely technical in nature since it opened late in September. But several crucial political issues are expected to be raised during the closing days next week.

At that time, the several working committees that have been meeting separately will disband, and the 2,000 convention delegates will begin meeting in regular plenary sessions to approve the more than 1,000 pages of proposals that will have survived the committee stage.