A super-advanced spacefaring civilization might need an extraordinary source of energy. As they move off their homeworld they will have to start 'beaming' energy wirelessly between locations. At first they may use Solar Concentrator Beam Power Satellites to power their space technologies. Eventually they may move closer to their Sun to take advantage of more intense radiation there. If mankind were fully mobilized for this purpose, it might take us thousands of years to achieve this. As this energy is beamed from the central star to various outlying colonies, our solar system would begin to generate multiple radio sources from multiple colonies.

Still further into the future, we may require more energy. Large arrays of highly reflective parabolic mirrors may be too costly to construct. It might be better if we only had to build low-cost lightweight rectifier antennas to collect energy. This would require the Sun to generate microwave or radio emissions instead of light. In the natural aging process of a star, this might take place several billion years in the future, after our Sun has used up its fuel and is an old dwarf star. Life might persist by somehow altering the spectrum of solar energy emitted by the Sun and generating electricity with the radio waves collected.

Billions of years in the future, we might discover radio sources popping up all over the Milky Way. Billions of them. An observer in another galaxy might then classify ours as a radio galaxy.

Mechanism of power generation? Back to radio galaxies... from this article...

"The radio waves coming from double-lobed sources are undoubtedly synchrotron radiation, produced when relativistic electrons (those traveling at nearly the speed of light) emit a quasi-continuous spectrum as they gyrate wildly in magnetic fields. "

"It is now believed, largely because of the work of Sir Martin Rees and Roger Blandford, that the nucleus of an active galaxy supplies the basic energy that powers the radio emission, the energy being transported to the two lobes by twin beams of relativistic particles."

Enhancement and control of a solar magnetosphere might create the conditions necessary for a star of any type to generate relativistic electrons, which then emit radio or microwaves. In our solar system Jupiter is the planet with the largest magnetosphere.

Check out this abstract from JPL!!!

More stuff on Synchrotron Radiation:

here

here. What's interesting is that 2.45 GHz was the frequency proposed for power transmission. It's not an absolute, but merely that most biological things are transparant at this band and not harmed. Only the antenna would absorb the energy. Elsewhere in the galaxy this might not be a restriction.

here

Sciennnnceee!