A West German businessman was given a six-month suspended sentence in federal court in Alexandria yesterday for aiding the illegal export of high-technology devices believed destined for the Soviet bloc.

Klaus Talleur, 50, a West German consulting engineer, had pleaded guilty Monday to filing a false U.S. Department of Commerce statement to facilitate the illegal shipment of microwave circulators to an Austrian firm serving Soviet Bloc countries. The microwave devices enhance military communications systems.

Talleur's attorney, William S. Taylor, said his client voluntarily returned from Hofheim, near Bonn, last month to face the two-year-old charges against him in part because his consulting business has "suffered tremendously after the indictment."

He will be allowed to return to West Germany under the sentence. Two of his biggest customers, Taylor said, had been the U.S. and West German governments.

In 1983 a Falls Church man, Gunther R. Nachtrab, was sentenced to 90 days in jail for violating federal export laws when he shipped 65 microwave circulators to Talleur's West German firm.

The devices, purchased by Nachtrab in 1981 from a California firm for $12,772.75, cannot legally be sold to any country except Canada without a special license issued by the Commerce Department.

Talleur's willingness to talk to federal investigators contributed to his suspended sentence and the dismissal of charges of export law violations, said Assistant U.S. Attorney Joseph Aronica. The prosecutor said the government is becoming increasingly concerned with the rising number of cases involving the sale of high technology to the Soviet bloc, particularly through Austria.

"There has been a stepped-up campaign to stem the illegal outflow of advanced U.S. technology," said Donald Creed, a Commerce Department spokesman. In 1984, the government prosecuted 51 cases involving violations of federal export laws, a 38 percent increase from 1983, according to Creed.

Aronica said most individuals believed aiding Soviet bloc countries with U.S. technology usually are prosecuted for lesser offenses because of the difficulty in tracing the direct connection between Austrian or other European firms to the Soviet bloc.

Compounding the problem of enforcing federal export laws are the volume of goods shipped out of the country and the difficulty in assessing whether a tiny electric component could endanger security.

Federal agents began investigating Talleur when two of Nachtrab's employes reported that goods were being exported from his Falls Church firm without proper papers.

When a 20-count indictment was returned against Nachtrab on April 14, 1983, it also named Talleur, Anna Landua, an Austrian who has since died, and Jeannette Wellems, an Austrian still at large.