Like virtually all its ideological adversaries in the capitalist world, the Soviet Union expects a disappointing economic performance in 1980.

State planners have revised downward most major indicators from the original five-year plan targets for the year, a galling but unavoidable action in the face of continued lags in such fundamental areas as electric power, oil, coal, timber and paper.

In all, the Soviet national income, as Russian economists call their gross national product, is planned to rise 4 1/2 percent over last year, not bad when compared with the expected 1980 results in the United States but far below what the state expected of its industry and agriculture five years ago when the 1976-1980 economic program was laid down by the ruling Communist Party Central Committee.

Russia is largely insulated against the inflation and recession plaguing the West, but its economy has other severe problems that the Kremlin Politburo under Leonid Brezhnev has failed to deal with in a comprehensive manner during his 15-year reign.

These areas lie in an aging, undercapitalized and inefficient industrial sector, grossly inefficient and wasteful agriculture and transport, and insufficient worker incentive to improve per-capita output.

In the world of planned economy, the economic traveler used to the general workings of the marketplace soon finds himself in a bizarre environment filled with relationships that would try even the ingenuity of Jonathan Siwft. Let us take an example that has had Moscovites laughing for months since it first was reported: the factory that manufactures metal camping ware and fry pans.

Under Soviet economic rules, the productivity of this factory is measured by how much material it consumes, not how many units it produces. The essential link between worker and productivity is thus broken.

In the case of this factory, which has been described in some detail by officials, the managers wisely decided that by increasing the input of metal they could get bonuses for exceeding their plan. But the workers disliked the idea of incresing their output. How to get around the dilemma? After furious thought, the problem was solved: produce heavier camping ware. Soon the factory was earning bonuses while hapless campers were getting sprained backs.

In the same way, there is little incentive for factories to find more efficient ways to stamp out metal parts, because the more scrap, the more material used, even though the workers toil no harder or faster. In a stern November economic address to the Supreme Soviet, Brezhnev sharply denounced such waste.

The topsy-turvy rules apply to a factory work force as well. Because a manager never knows when the local commissar will show up to recruit a work gang to dig potatoes before they rot in the fields, he keeps extra bodies around on the payroll so his assembly lines won't be interrupted by the press gangs assembled to solve frequent harbest crises. But no matter: the bigger his payroll, the more money he gets from the state for welfare and recreation programs for the workers. Either way, there is little detectable pressure in such a system to look for efficient ways of doing things. Besides, if he finds them, streamlines his production line and trims off the excess workers, who will be left to dig potatoes?

Unlike their East European clients, the Soviets have staunchly staved off any experiements with mixed market and planned economies. Some stirrings of reform in the mid-1960s backed by Premier Alexei Kosygin, who runs the economy as chairman of the Council of Ministers, were squelched by Brezhnev and his supporters in the Politburo. Since then, the U.S.S.R. economy, which averaged 5 1/2 percent annual increases in 1966-70, has been averaging increases of well under 5 percent each year.

As the factory example shows, it is difficult to inspire higher production under such a system.

Even so, the Russian GNP is a powerful economic force that has pushed living standards generally upward and made the country the world's largest oil producer. It annually earns about half its $6 billion in hard currency from oil exports, giving Moscow a powerful leverage in dealing with its capitalist European neighbors.

The Russian economy also has supported a fundamental technological revolution in its armed forces, giving the country in 1980 such sophisticated weapons as the nuclear-tipped SS-18 and SS-20 milliles, the world's finest operational heavy tank, the T-72, and the most lethal close-support helicopter now flying.

As the Afghanistan invasion shows, the Soviet armed forces have achieved the capacity to project their cadres quickly and efficiently, and long-range Soviet military airlifts to Africa and other far-away points in the 1970s drove home the face that the military industrial base is thriving.

Economists at the state planning committee, Gosplan, are hard at work drawing up the outlines of the next five-year plan for 1981-85 to be adopted at the 26th party congress expected in the spring of 1981.

In the aftermath of the American reprisals against Moscow for the Afghani invasion, it is impossible to say how much the Soviets expect to -- or can buy in the West of the advanced technology they need to incease worker productivity, which expanded by just 2 percent last year, a post-war record low.

The U.S. embargo of 17 million tons of feed grain for Soviet livestock imposed by President Carter Jan. 4 is expected to have a major impact on meat production in 1980. Many incentive programs for workers include special fresh meat rations, so it seems likely factory managers will have further trouble finding viable internal incentives to raise productivity.

Some Soviet sources suggest that the grain embargo ultimately may hasten long-overdue agricultural reform in the new decade, but again that seems more a function of Brezhnev's longevity in power rather than any other factor.

During his years at the top, Nikita S. Krushchev once boasted that the Soviet Union's economy would match American's by 1980. That year is now at hand. The Russian economy is about 60 percent the size of America's, and this year will be no more promising than last year in closing that gap.