In fact, one of the things that SETI transmission back in the 70's did was to spike certain frequencies well above what would be expected from Sol. The Sun is a great transmitter, but keeping our transmits restricted to certain frequencies and at a generally steady broadcast would make us appear to be hotter than the sun, electromagnetically speaking that is. The sun, however, probably drowns us out with amplitude. With the right filters, Earth would be very noticeable -- at about 100+ light years -- our radio-lifetime -- and getting louder with time.

Contrary to popular belief, not all radio signals escape to space. Many are contained within the envelop of the Earth's atmosphere through refraction, diffraction, and scattering. With proper QC, the only signals that should get out with any real power are those designed to, such as satellite and telemetry signals. Even then, frequencies designed for space might find it difficult to get there, with such natural propagation issues as humidity, rain, scintillation (them’s sunspots), and airborne ice crystals.

Anyway, signal loss to space is a given, but we are getting cleaner with it -- so maybe the Earth’s electromagnetic signature is fading?

Dan