For those who had hoped this year's presidential election would open the door to national unity and international respectability, the announcement last weekend that Gen. Angel Anibal Guevara will be Guatemala's new head of state brought only gloom and a sense that little had changed here.

Among the disappointed were the three losing candidates, conservatives of varying stripes of respectability who bitterly charged that this election, like so many others in the past, was a fraud orchestrated by the military.

Although the U.S. Embassy remained diplomatically circumspect as the National Congress officially declared Guevara the winner Saturday, officials there clearly had been hoping the election would bring a marked change in Guatemala's long and increasingly disastrous history of military-dictated governments.

More significantly, disappointment has swept through a wide range of the nation's business and landowning elites, and appears to have shattered the mutually reinforcing alliance between them and the nationalistic military men with whom they have ruled for nearly three decades.

Despite campaign promises of a "new era," Guevara, the official candidate, was widely perceived as the representative of continuismo, the continuation of the government of retiring President Romeo Lucas Garcia. A political clone of Lucas, Guevara, too, is a former defense minister tapped for the presidency by the armed forces high command.

The triumph of the government's candidate for president was, in retrospect, hardly surprising in a nation with a sad history of electoral fraud, rigged votes, results vetoed by the military and coups d'etat. The real surprise was the uncharacteristic political isolation of the Army and its coalition of front parties after Guevara emerged from the balloting March 7 with a commanding, if hotly disputed, lead over his rivals--Mario Sandoval Alarcon, Alejandro Maldonado and Gustavo Anzueto.

Although there has been no conclusive determination of whether the election was rigged, the losers who charged fraud noted that even by the government's count, Guevara had only won 16 percent of the total possible vote of Guatemala's 2.3 million voters. The losers said that collectively they represented the true will of the electorate.

More surprising still was the spectacle of the losers and their supporters, all persons of varying positions within the right, taking to the streets like leftists to protest the victory of the lone military candidate in the election.

"We are in danger here of having a situation like in Nicaragua under Somoza where not only the left was alienated from the government but the right too," a coffee planter fresh from a demonstration told a visitor whom he joined to watch police tear-gas and beat other demonstrators in front of the National Palace.

"The danger is the left will take advantage of the situation and we will end up losers twice over."

That possibility exists in the long term given the growing strength of the four leftist guerrilla movements fighting the government in the highlands. But political analysts here say that in the short term the political power of the armed forces, under the forceful leadership of the president's brother Brig. Gen. Benedicto Lucas Garcia--who was educated at the French military academy St. Cyr--will prevail.

Although some of today's angry politicians may eventually appear in Guevara's government when it takes office July 1, the disenchantment of a large segment of the Guatemalan oligarchy has already become an important new factor in the tangled political situation.

Suspicions that the vote, which President Lucas repeatedly promised would be free and open, was manipulated once again in favor of the Army's candidate, have angered many businessmen and landowners.

Redemption of Guatemala's abysmal international reputation--and presumably redemption of the nation's negative credit rating--were to have flown from truly democratic elections which, it had been hoped by U.S. officials as well as concerned Guatemalans, would have brought forth a popularly based government, able and willing to distance itself from President Lucas' heavy-handed, often inept and corrupt, policies.

This was the "self-help" publicly urged on the eve of the elections by U.S. Ambassador Frederic Chapin as a condition for the United States to resume much-needed economic and military aid suspended in the late 1970s following Carter administration criticism of repeated and blatant human rights violations here.

A large group of Guatemalan businessmen and cotton and coffee plantation owners, banded together in their professional associations and a civic group named Amigos del Pais (Friends of the Country), campaigned tirelessly in the United States and here to convince themselves and foreign critics that free elections could and would be held.

Long allied with the military, which had acted as guarantors of the privileges of their class, these so-called oligarchs have sought to distance themselves from President Lucas in direct proportion to the threats of national bankruptcy that are an offshoot of his hard-line policies of curbing all dissent, or suspected dissent.

Between the cost of fighting a growing guerrilla war without any serious foreign military aid, with banking credits dried up because of international repugnance over the tens of thousands of civilians who have died during his four-year rule at the hands of "death squads," and the investment climate chilled by the Sandinista revolution in Nicaragua and the increasingly hot guerrilla war in neighboring El Salvador, Guatemala's economy today is verging on collapse.

The 6 percent growth rate Guatemala enjoyed for years until 1977, the year before Lucas was elected to the presidency, has plummeted to almost zero. The country's $830 million foreign exchange reserves that Lucas inherited were virtually exhausted in February when a bank consortium refused to roll over a $75 million debt forcing the Guatemalan treasury to kick up their last reserves to avoid international bankruptcy.

It is this state of affairs, more than concern for the human rights violations, that has suddenly frayed the traditional alliance between the Army and Guatemala's oligarchy.

It is this same state of affairs that last week led the very representatives of Amigos del Pais who had lobbied so hard all week to convince visiting journalists that Guatemala did not deserve its ugly reputation abroad, to finally throw up their hands in despair when the tabulation of electoral votes suddenly broke down and the election returns room they had set up to demonstrate Guatemalan democracy in action had to be closed for lack of returns to chalk up on its embarrassingly empty blackboards.

"This is the way the Guatemalans make elections," a suddenly embittered manufacturer in a group burst out to visitors, insisting later that he not be quoted by name lest he be targeted by government security agents. "Those in power, the military, always refuse to give up their power."