Cape Cod residents, afraid of potentially deadly microwave radiation, said yesterday they plan to return to federal court to stop the Air Force from turning on a massive new radar unit designed to protect the eastern half of the country.

The controversial $55 million PAVE paws (p/hased Array Warning System) radar facility at Otis Air Force Base is to begin scanning the sky for sea-launched ballistic missiles in April -- about the same time an environmental impact study on the safety of the unit is scheduled to be released.

A suit filed last year by the Cape Cod Enivronmental Coalition questioning the biological effects of long-term exposure to low-level microwave radiation has been in legal limbo awaiting the outcome of that report.

However, after reviewing a draft of the study issued in December, Anne M. Vohl, the coalition's attorney said, Monday, "If the environmental impact statement is not drastically changed, we will seak an injunction."

The study by the California-based Stanford Research Institute, which received $30.3 million from the Defense Department in fiscal 1978, states, "There is no reliable evidence from which to conclude any ill effects from exposure to PAVE PAWS radiation."

Added Lt. Col. David Kanter, "The benefits of PAVE PAWS appear to be more important than the very insignificant environmental impacts."

However, residents and scientists, testifying at the final public hearing on the study Monday night, contended the 188-page document is significant in its failure to prove the facility is safe.

Paul Brodeur, author of "The Zapping of America," a doomsday chronicle of the effects of microwave radiation, called the initial report "a dishonest, evasive piece of pseudo-scientific trash."

Dr. Robert Windsor, an MIT-trained engineering physicist also assailed the report as "far from unbiased... unscientific... it has serious limitations. How many Cape Cod residents must be injured to obtain an Air Force objective?"

"We happen to be a guinea pig population," said Margaret Ellsworth, a local artist.

The environomentalists face a lonely legal road in their battle against the Air Force because microwave radiation is currently not regulated by any Federal agency, although some departments have set voluntary standards.

The Air Force conducted the environmental impact study measuring radiation levels on the resort peninsula only after presure from angry residents and political leaders.

"On this issue, the resolution will have to be political rather than legal," said Vohi. "The legal process opens the forum but doesn't resolve the issues."

Since the Air Force is not required to seek a permit from any federal agency for permission to build the radar station, it is not bound to prove that the long-term effects of microwave radiation are harmless, according to Joseph McCabe of the Environmental I rotection Agency's Office of Federal Activities.

The environmentalists, however, must prove to the federal court that the radar emissions are dangerous before they can block its operation.

"Can you guarantee us that the PAVE PAWS radar facility is safe to human beings?" asked one worried resident.

"I am not God; I do not know the future," replied Col. George Mohr, a Harvard-trained Air Force flight surgeon. "The radiation levels do not indicate this is a hazard to your health."

Brodeur, an environmental writer for the New Yorker magazine, has spent several years convincing his neighbors here that the low-level radiation from PAVE PAWS and an older facility at the tip of the Cape that has been irradiating residents for 20 years can cause blindness, birth defects, cancer or enen death.

Cape Cod residents point out there is still no conclusive study showing that microwave radiation -- which falls at the opposite end of the electromagnetic spectrum as nuclear radiation -- is safe.

"If microwave radiation were a food or drug," said Brodeur, "it would have been banned by now."

The Air Force notes that the new radar facility will generate a $4.7 million annually to the local economy and will provide about 200 jobs.

And early "environmental assessment" conducted by the Air Force and approved by the EPA showed "no adverse health effects." The new study is scheduled to be reviewed by the EPA and 14 other departments and agencies.