National Public Radio, which is anticipating sharp reductions in federal support, is moving into commercial communications ventures in the hope of earning revenues that will lead to financial independence.

In recent weeks, NPR has signed an agreement with Western Union to sublease to commercial users NPR's excess time on Western Union satellites, and has reached agreement with a McLean corporation for a joint venture to transmit digital information to homes and offices.

But NPR has dropped a proposal to take over the money-losing United Press International news service, NPR officials said.

NPR's directors voted 7 to 6 in January to examine the feasibility of accepting the news agency as a tax-free gift from E.W. Scripps Co., which owns 95 percent of UPI. But NPR decided that it could not take on UPI, which has been losing money for years, "unless somebody wants to give us $10 million a year to support it. That deal is dead," a spokesman for NPR said.

Budget cuts proposed by the Reagan administration are expected to reduce NPR's grants from the parent Corporation for Public Broadcasting from $14.6 million to $11 million in the next fiscal year. Because NPR already is balancing its budget through its own earnings of about $3 million a year, the amount it will need to raise annually will grow to more than $6 million when those cuts are implemented. In a speech to the Public Radio Conference here last month, NPR Executive Vice President Thomas C. Warnock said NPR has been "sorting through dozens of ideas" for raising the needed revenue.

The agreement with Western Union allows NPR and Western Union to market commercially the unused capacity of NPR's leased channels on Western Union's Westar satellites. NPR or Western Union will share revenues from subleasing of satellite time, regardless of which one makes the sale, according to NPR officials.

NPR's digital information experiment involves forming a joint venture with National Information Utilities Corp. of McLean.