ANNAPOLIS, SEPT. 16 -- To sway a public that is "frankly confused," Maryland Stadium Authority Chairman Herbert J. Belgrad said today the authority will hire a public relations firm to convince Marylanders that a stadium complex in downtown Baltimore is a good idea.

Belgrad said that while the state and the authority were able to persuade the Maryland Court of Appeals to prohibit the stadium proposal from going to public referendum, "we have not been as successful in winning public support for the project."

"The public is frankly confused," Belgrad said.

The public relations firm will be paid from contributions from Baltimore business leaders and corporations, Belgrad said, as well as money from the six or seven groups that have expressed interest in trying to bring a National Football League franchise to Baltimore. Belgrad is asking each of the groups for $100,000 and though none has written a check, he said prospects are good that each will contribute.

Last week, the court said by a 6-to-1 vote that a petition drive to place the stadium project on a November 1988 ballot violated a constitutional prohibition against holding referendums on state appropriations acts. More than 44,000 signatures had been collected in the petition drive.

Belgrad said the public relations firm would not only answer public concerns about the stadium project and try to generate statewide enthusiasm, but also would work to convince the NFL that Baltimore deserves an expansion team.

The NFL will select a committee next spring to review expansion plans, and Baltimore, Oakland, Phoenix, Memphis and Jacksonville are all vying for the two teams that NFL Commissioner Pete Rozelle has said will be created.

Belgrad said Baltimore is behind in the contest, and the city's rivals made sure that each of the 28 owners knew about the referendum effort aimed at killing the stadium plan.

"We have to be able to demonstrate to the NFL that the support {for the project} is in fact broad-based," Belgrad said. One way to begin might be to sell season tickets to the proposed team, he said.