In 1984, the world's most powerful satellite communications organization will move from its obscure quarters in L'Enfant Plaza to a striking $50 million complex of modern buildings just off Connecticut Avenue NW.

For the International Telecommunications Satellite Organization (Intelsat), which will mark its 20th anniversary that year, the move represents a sharp change in visibility at an auspicious time in the dramatic development of satellite communications.

As the flashy new quarters make Washington-area residents suddenly more aware of the organization, the world will be on the verge of entering an entirely new day in satellite technology and is likely to begin a new phase in the business of international communications, an area dominated over the last two decades by Intelsat's virtual monopoly position.

Across the world, from France and Britain in Europe, to the Arab nations in the Middle East and Indonesia in Asia, many nations are getting into the satellite communications game. And profound questions are being raised about Intelsat's structure and about how the free flow of electronic information will pass from nation to nation as the decade progresses.

"There are already the beginnings of some fairly heavy fights in the space area," said Mary Jo Manning, an international communications expert and a partner with the law firm of Hedrick and Lane. Manning is also a former Senate counsel who worked on satellite issues. "There is also a lot of pressure for regional satellite consortiums, and Intelsat could provide a model. But other countries, like England or France, look at Intelsat and say 'maybe we could make money if we put our own satellites up.' "

Another observer, Jonathan Miller, editor of Satellite Week, goes a bit further. "The role of Intelsat will change," Miller said. "It makes a huge profit and it has done a good job. But profound technical and political changes are coming and it will no longer be true that Intelsat will have its de facto monopoly."

Satellite experts and Intelsat officials agree that Intelsat, a cooperative venture currently involving 106 owner countries, is a model of international cooperation. There is little question that since its founding Intelsat has been largely responsible for the giant strides that have been made in linking the world's telephone, television and data communications systems.

"As international organizations go it is probably an ideal organization," said Walter Morgan, a consultant with The Communications Center in Clarksburg, Md. "It is amazing to ponder the fact that 100 countries with a wide variety of ideologies seem to fit under one roof. In this particular case, telecommunications has indeed united the world."

There is little doubt that Intelsat is responsible for bringing about a new world communications order. The organization's satellites handle virtually all transoceanic television traffic and most of the intercontinental telephone traffic.

But few people outside the communications business know exactly what Intelstat does, and its uptown palace is likely to confound commuters, students at the University of the District of Columbia and residents of the nearby community.

Intelsat officials say the public knows little of its mission, structure and operations because its work -- international satellite transmission -- is performed almost without a hitch. "One of the reasons we are obscure is that we do what we do successfully," said Joseph N. Pelton, executive assistant to Intelsat Director General Santiago Astrain.

For example, it is Intelsat's systems that brought 1.3 billion people more than 4,000 hours of the World Cup soccer matches this summer. "Never before have so many people participated in one event," said H. William Wood, Intelsat's deputy director general of operations.

Not only have Intelsat activities affected millions of people by ensuring that international communications is a routine activity, but it also has been the major spur to the development of the satellite construction industry, a thriving multibillion-dollar business. This year, for instance, the company announced a $1 billion satellite construction contract with Hughes Aircraft Co., the largest such contract ever announced.

But when Intelsat was formed in 1964, only 11 countries were involved, and before that time only underwater cable was available for transoceanic television and telephone service.

By mid-1965 the first Intelsat satellite, Early Bird, was launched into orbit. By the end of that year, however, there were only 75 full-time satellite telephone circuits in operation, a figure that will rise to 30,000 by the close of 1982.

Through those early years Communications Satellite Corp. (Comsat), the designated U.S. representative to Intelsat, provided Intelsat with its management, although the member countries, under a complex arrangement, own shares in the organization.

In 1974, however, a new agreement among the member countries was drawn up, in effect splitting off Intelsat from Comsat's management. Since then, Intelsat has had its own staff, now up to almost 550 people, nearly all of them in Washington. The new quarters, in the first construction phase, will be able to house 800 staff members.

As the staff has grown, so has the Intelsat system. It now consists of 16 satellites, with that many on order. System traffic is growing at about 25 percent a year, a figure expected to slow soon to 20 percent.

Although basic service costs have dropped, total revenues have continued to rise, from $216 million in 1980 to an estimated $320 million this year. Meanwhile, Intelsat's operating budget has soared from $1.2 billion last year to $2.3 billion in 1982 -- generally due to the Hughes contract.

The basic technology, of course, has changed almost as quickly as signals today beam across oceans. For instance, the Early Bird satellite had capacity for 240 voice circuits and one medium-quality black-and-white television channel.

The organization's latest satellite series, Intelsat VI, which will begin launchings in 1986, will have a capacity of up to 36,000 telephone circuits and two color television channels. With that capacity, it would be able to transmit the Enclyclopedia Britanica across the Atlantic Ocean 20 times a minute.

But as technologies, like those used by Intelsat, have become perfected, linking the world in ways that few thought possible when Intelsat came into being, the world has come to expect more and more of satellite communications. In addition, other technologies, like undersea cables that will be operated by firms such as American Telephone & Telegraph Co., offer alternatives to Intelsat.

With new transmission systems have also come new challenges for Intelsat management. "Intelsat's basic position will have to be one of adapting to the new environment," Pelton said. As a result, the organization is spending millions of dollars in research, looking into new areas, particularly in business data and video-conference technology and new satellites like multipurpose space platforms.

"The basic idea is to make certain that the original purpose of creating a global interconnection on a cost-effective basis is maintained," Pelton said. In effect, Intelsat's lucrative, high-traffic links between places like the United States and Western Europe help fund the pieces of the system that get less usage, particularly to developing countries.

In a 1981 paper, Pelton said without citing specific examples, the development of regional satellite systems, such as Arabsat, linking countries in the Middle East, could raise questions about the viability of Intelsat's cost system.

Pelton said the "proliferation of regional satellite systems" could "serve to diminish and perhaps ultimately eliminate the economies of scale which have been of importance to Intelsat's evolution into an extraordinarily efficient and cost-effective global communications network."

Others, however -- notably some Europeans -- are less certain about where Intelsat should be heading. Louis Mexandreau, a French government minister, told Intelsat's annual signatories meeting in Paris in May that Intelsat ought only to be a conduit for new satellite services and "should not have direct contacts with its clients. . . It is not its role . . .

"The organization should rather look to get the best profit" from the "gamut of services which it already offers," he said.

Mexandreau said that instead of moving into new ventures Intelsat ought to focus on building its television and telephone traffic in order to assure its continuing profitability.

But Morgan, a former Comsat executive who knows Intelsat intimately, said that the concerns can be exaggerated and that both critics and Intelsat ought to be able to utilize the benefits of new regional systems.

"I'm coming to the conclusion that that there is room for many different types of systems on a multinational basis," he said. "They all don't have to to be TWAs or Intelsats in a carefully manicured way. Small subsystems can be feeders, just as they are in the airline business."

Intelsat's new building, on a protected wooded site off Connecticut Avenue between Tilden and Van Ness streets, was designed by an Australian, John Andrews, who says it is "designed in a spirit of openness, of faith, of cooperation between people and groups of people." CAPTION: Picture 1, Intelsat's satellite control center at its L'Enfant Plaza headquarters, which will be moved in 1984 to $50 million complex in Northwest D.C.; Picture 2, Santiago Astrain, director general of Intelsat, which has enjoyed a virtual monopoly in international satellite communications. Photos by Larry Morris -- The Washington Post; Picture 3, Intelsat executive Joseph N. Pelton.; Picture 4, Artist's rendition of Intelsat's modern $50 million complex being built off Connecticut Avenue between Van Ness and Tilden.