The potential buyers won't look, sound or bid like the art and antique aficionados and professionals who usually attend Sotheby Parke Bernet's New York auctions.

But about $100 million might change hands next month when some 50 media moguls bid in an unprecedented auction at the renowned Manhattan gallery.

What the executives from broadcasting and publishing concerns will be bidding for are the limited slots aboard RCA's Cable Net II satellite.

"It's not going to be like a tobacco action," promises Dennis Elliot, the vice president for finance of RCA American Communications Inc. "It will be done in a dignified way."

RCA, which still needs Federal Communications Commission approval for the plan, is taking a new tack in the increasingly high-stakes competition for transponders on commercial communications satellites. Company officials announced yesterday plans to auction seven transponders at Sotheby on Nov. 9.

Similar transponders--small units aboard satellites that receive and transmit the signals which have created the cable television boom--have been selling or leasing for reportedly as much as $13 million a piece in recent months.

The amounts of the winning bids will be applied against the monthly lease payment beginning in 1982. RCA officials would not speculate on how high the bidding might run. "We don't even have a clue," said Andrew Inglis, president of RCA Americom.

About 50 applications to participate in the bidding have been accepted by RCA, all filed within days of the company's preliminary announcement that an auction was planned. But not until the bidding is finished can RCA let the FCC know what the rates for the space will be. And when those rights are sold, the winners are virtually free to resell the rights to others.

The leases expire in 1988, and the two satellites have yet to be orbited. The launches are scheduled for Nov. 19 and Jan. 12, and payments would be due within 10 days of the Jan. 15 date when the rates go into effect.

In the past, access to these transponders has been granted on a first-come first-served basis, at times for simply the price of a postage stamp. "This relieves both RCA and the FCC from making value judgments," Inglis said. "No one has to decide one company is more worthy than another."

A recent FCC staff report suggested that auctions might be fair means of determining who really needs the transponders, and the concept has a bit of a fashionable deregulatory ring to it.

Inglis, noting RCA's $350 million commitment to its satellite program, also argues that the commission ought to approve the auction scheme because it rewards risk. "There is a matter of elemental fairness here," he said.

The company officials insisted that the auction's purpose is to assign the transponders, although they admit the up-front payment would permit them to invest and utilize the money they receive.

RCA also says, however, that the transponders are worth more than their regulated rate.