The downward trend in voter participation may have bottomed out, according to a new Census Bureau report on the 1980 election.

According to the report, 59.2 percent of those surveyed two weeks after the 1980 election said they had voted, the same figure as in 1976. Until then, participation, which was more than 69 percent in 1964, had been dropping steadily, to the concern of political scientists and civic-minded citizens.

The survey also showed that men and women now have the same voter participation rate, a change from the past when a higher proportion of men voted.

Except for these two changes, the survey, which measured the percent of the total voting-age population of 18 or over who voted, primarily confirmed past voting patterns.

Participation differed sharply among different racial, economic, occupational and residential groups.

For whites, voter participation was 61 percent, for blacks about 51 percent and for Hispanic-Americans about 30 percent.

The Hispanic percentage was low because the basic group surveyed included many noncitizens who can't vote. The Hispanic rate would have been about 44 percent if only citizens were counted. The percentages of whites and blacks also would have been higher if noncitizens had not been counted, but only slightly, 63 and 52 percent, respectively.

The survey showed that voter participation increases with age: only two-fifths of those from 18 to 24 voted, three-fifths of those from 25 to 44 and about two-thirds of those 45 and above.

Regionally, voting was highest in the Midwest, with 66 percent, followed by the Northeast with 59 percent, the West with 57 percent and the South with 56 percent.

Education and income correlated directly with voting. Low-income people and those with only an elementary school education or less had the lowest rates, about two-fifths; the percent rose steadily with higher income and education, and was 74 percent for those with a family income of more than $25,000 and 80 percent for those with a college degree or advanced degrees.

White-collar workers had much higher participation rates, 71 percent, than farm workers, 60 percent, service workers, 51 percent, and blue-collar workers with 48 percent.

The voter participation rate was much higher for homeowners, 68 percent, than for renters, 45 percent.

Although the overall voter participation rate was only 59.2 percent, the survey showed that a major problem was that people didn't register; of those who did, nearly 90 percent voted.

About 37 million people who were citizens and therefore could have registered did not. Asked why, 8.5 percent said they didn't prefer any of the candidates, and another 39 percent said they just weren't interested in the election.

The survey also shows that some people are ashamed to admit they didn't vote, and tell the counters they did.