The dollar rose sharply and gold prices fell today as traders scrambled to buy dollars when rumors circulated that U.S. authorities were planning further measures to keep the dollar stable.

The dollar finished with a 1.7 percent gain against the West German mark, a 2.4 percent rise against the Swiss franc and a 1.1 percent advance against the yen of Japan.

As far as could be determined, central bank intervention in support of the dollar wasn't particularly heavy. Gold closed in London at $219.75 a Troy ounce, off $5.45 from Tuesday.

One source of speculation about further U.S. measures was an article in the Frankfurter Allgemeine Zeitung which said the Carter administration couldn't afford to let the dollar keep dropping and that further measures to defend the currency were in store.

Market operators evidently were in a bind because they built up large "short" positions by borrowing dollars and converting them into other currencies, essentially speculating that the dollar would decline. Hence, there was a rush to take profits on the dollar's recent decline now by repurchasing dollars even though there wasn't any confirmation that U.S. authorities are planning new measures.

The dollar closed at 1,8480 marks up from 1,8175 late yesterday. The day's trading range was abnormally wide with a low of 1,8210 and a high of about 1,8560.

German balance of payments figures released today indicated that multinational corporations had continued to shift funds into marks in November, through adjustments in their import and export patterns.

In trading for Swiss francs the dollar jumped 3.8 centimes to 1.6470. The U.S. currency also advanced to 4.2350 French francs from 4.16 and rose to 196.55 yen from 194.35. Sterling declined to $2.0250 from $2.0363, which represented a smaller decline than posted by other major currencies. Meanwhile, the British Treasury disclosed that the nation's reserves rose by $25 million in December to $15.7 billion. A dealer said the reserve figures indicate Britain's external finances seem to be in good shape.

The Canadian dollar closed at 84.12 U.S. cents, up from 33.98 cents yesterday in moderate trading.