Despite a successful debut by special negotiator Robert Strauss, the Egyptian government believes any substantial progress in Palestinian autonomy talks probably will require another personal intervention by President Carter, qualified sources say.

Egyptian officials are quick to praise Strauss and they appreciate his personal access to the White House. But at the same time, experience has demonstrated that only Carter's direct involvement can produce decisions on such "essential" subjects as control of the West Bank, they say.

This view seems to foreshadow a largely preparatory role for the current autonomy negotiations. The next round of the negotiations is scheduled for Aug. 5 at Hertzlia, Israel. They have been alternating between Israel and Egypt since they opened in Beersheba, Israel, on May 27. Once the underbrush is cleared away in these talks, the officials said, Egyptian President Anwar Sadat, Israeli Prime Minister Menachem Begin and Carter inevitably will have to wrestle with the key issues in person as they did at Camp David and during Carter's dramatic negotiating trip to Egypt and Israel.

"The history of the negotiations has shown that at some point the three principals will have to become involved," a high-ranking Egyptian official remarked.

"They're trying to get around it now," said another, "but sooner or later, they'll have to face it."

This point likely will come late this year, diplomatic observers say. U.S. Egyptian and Israeli diplomats involved in the negotiations have said the late fall or early winter has become a psychological target date for demonstrable progress.

Next October is the sixth anniversary of the 1973 Middle East war that Egyptians depict as the first step on Sadat's road to peace. In addition, November will mark the second anniversary of his trip to Jerusalem. Egyptians are eager to have some gains on Palestinian autonomy by then as proof Sadat did the right thing in signing the treaty with Israel despite the outcry from most other Arab nations.

Until then, Egyptian officials predict negotiations on autonomy for Gaza and the West Bank will proceed on three levels: the regularly scheduled talks shifting between Hertzlia and Alexandria, Egypt, more summit meetings between Begin and Sadat, and direct contact between Begin and Carter on one hand and Sadat and Carter on the other.

Begin and Sadat met last week in Alexandria and are scheduled to meet again at the end of August in the northern Israeli port of Haifa. Following that, Israeli officials said in Alexandria, another meeting probably will be scheduled relatively soon as part of a series of regular contacts between the two leaders.

But, a high Egyptian official said, a meeting between Carter, Begin and Sadat probably will still be necessary to make "essential decisions," such as the degree of autonomy to be allowed West Bank Palestinians or eventual participation of Palestinians from outside the West Bank in the negotiations.

This conviction reflects Sadat's long-held belief that only the United States has enough influence with the Israeli government to get the kind of concessions regarded here as indispensable.

U.S. diplomats here say Ambassador Strauss had to push hard during the last round of negotiations in Alexandria just to win agreement on procedural points. Egyptian and Israeli negotiators had argued fruitlessly about an agenda until Strauss's forceful intervention.

In their one-on-one talks last week, also at Alexandria, Begin and Sadat seemed to have established an authentic rapport despite disagreement on key issues, their aides said. But this was achieved essentially by avoiding any bargaining on such thorny problems as Israeli settlements on the West Bank or the nature of Palestinian autonomy there, they added.

The personal rapport led to some minor agreements on oil sales, the possibility of rebuilding a partially destroyed rail line between Egypt and Israel and the return of the Mount Sinai area to Egypt in advance of the schedule spelled out in the peace treaty.

It is when Begin and Sadat can no longer skirt the difficult problems that the matter of Carter's intervention will come up, Egyptians say. By then, the political climate in the United States may influence Carter's willingness to get involved and the way he goes about it, they predict.

The general expectation among Egyptian officials and American diplomats involved in the talks is that as the negotiations go on, U.S. positions will fall closer to those of Egypt than those of Israel. This explains the reluctance of Israeli negotiators to see Strauss become such an active participant in the talks. It also explains Sadat's frequent insistence that the United States must remain a "full partner" as the negotiations move into the touchy West Bank issues. CAPTION: Picture, Sadat believes Carter can persuade the Israelis. UPI