Let's start with the basics, and work our way out to an answer. The distance to Proxima Centauri is about 40 trillion km. That leads to a power loss of 664 dB, an incredible amount. Compared to Voyager 1, which is currently about 20 billion km away, an increase in the channel power of 172 dB is required. That means making the signal 10^8 times more powerful to maintain the same level of power.
Okay, so what is the best that we could do? DSN uses a 70m antenna, Arecibo is a 300m antenna. That leads to about a 16 times increase in power. That covers a very small portion of the required power.
Let's assume somehow we had a 300m antenna on the spacecraft itself. Voyager's antenna is 3.7m. This is a 6500 increase in power, quite significant. Combined with the use of Arecibo, that would lead to a roughly 100,000 increase in power, or 100 dB. Of course, launching a 300m antenna is virtually impossible.
The bottom line is, this would be extremely difficult using RF power. Using visible is much simpler, as the required dish sizes are much smaller.
Bottom line, it would take an enormous increase in power to make interstellar communication possible, although