Northern Virginia Republican Frank Wolf ended a five-year congressional quest yesterday, riding the crest of Ronald Reagan's overwhelming suburban support to sweep three-term incumbent Rep. Joseph L. Fisher from his 10th District seat.

After waging one of the most expensive congressional campaigns in the state's history, Wolf crushed the liberal Democrat in the increasingly Republican Virginia suburbs. He bested the 66-year-old economist by a 52 to 48 percent margin, reversing 1978's result in Fairfax and Loudoun counties by amassing a 15,000-vote victory spread in those outlying areas.

The final unofficial tally was 106,000 votes for Wolf, 99,000 for Fisher. Uncounted absentee ballots were not expected to significantly alter the outcome.

Even in triumph, Wolf wore the frown that has become his hallmark. "I think he was numb," said his wife, Carolyn. "He was in a state of shock."

After fumbling at first for words, Wolf told joyful supporters Fisher had called to congratulate him. "He [Fisher] is a real gentleman," said the 41-year-old Vienna lawyer-lobbyist. "He's a good campaigner. I know what it is to be on the other side."

Conceding defeat early, a tight-lipped Fisher told tearful backers, "I don't have too many regrets. Whatever we did, we did with class. We win with class, we lose with class."

Some disappointed Democrats were less philosophical. "It's disgusting, that's what it is," sobbed Arlington campaign worker Karen Darner. "And that's being kind."

"This was not a referendum on Joe Fisher," said Lt. Gov. Charles S. Robb of McLean, next year's likely Democratic gubernatorial candidate. "It is a very serious indictment of the economy."

Fisher's defeat, along with that of 8th District Democrat Herbert L. Harris, made a clean sweep of Northern Virginia's "Watergate class" of liberal Democrats and sounded an ominous warning to party officials in the area. Though the district's tradition of ticket splitting continued, with a Democrat winning election to the Arlington County Board, it wasn't enough to save Fisher.

In Loudoun County, which Fisher carried by a 51 percent margin against Wolf two years ago, the tireless Republican challenger even outpolled Reagan. The rapidly developing outer suburb gave Wolf 11,000 votes to Fisher's 7,000.

Fairfax County Voters, who sided with Fisher by a slim two-point margin in 1978, gave Wolf an 11,000-vote edge. The two jurisdictions combined were more than enough to counter Fisher's 8,000 vote edge in Arlington.

After nearly 20 years of elected public service, incumbent Fisher found himself in much the same position as Joel T. Broyhill, the 11-term incumbent he beat six years ago to snare the seat for the Democratic fold. Republicans, who saw Broyhill as a victim of Watergate fallout, were counting on widespread voter discontent with the Carter administration to bring about a similar reversal in favor of Wolf.

Strategists on both sides tailored their campaigns accordingly. Fashioned by a $40,000 media consultant, and showing signs of considerable national GOP influence, the Wolf effort saturated the area with bumper stickers, placards and innumerable television and radio messages.

Wolf tried to cast Carter's name like a blanket over the Fisher candidacy, seldom missing an opportunity to remind voters that his opponent had "voted with this administration nearly 80 to 90 percent of the time." He recalled the incumbent's voting record on a few selected issues to accuse Fisher of being "asleep at the switch" during crucial congressional business.

Fisher, a ranking majority member on the powerful House Ways and Means Committee, "backed away from Carter as far as possible," said one Fisher aide. He even prohibited his volunteers from distributing his own campaign literature together with that of his party's standard bearer.

Up to the last day, Fisher loyalists feared for their candidate's survival, and with good reason. After his remarkable defeat of Broyhill in 1974, Fisher had smooth sailing in the 10th District until Wolf came along. In 1976 he won reelection by a 16-point margin, considered extravagant for the area, only to find Wolf "yipping at my heels," in Fisher's phrase, in a six-point victory in 1978.

In the last four years, Fisher's strength in the area had been slowly but steadily slipping. Democrats fretted over their diminishing presence on local boards and in state delegations. And in the increasingly Republican Virginia suburbs, 55,000 newly registered voters this year only added to uncertainty over how large blocks of transients and independents would make their congressional choice.

The ubiquitous Wolf, who won his party's affections in part through sheer determination, brought to the race a doggedness that made admirers out of some of his Democratic adversaries. The vituperation that marked his effort of two years ago was smoothed away by his seemingly improved chances.