I have somewhat always believed something like this.
The period of time you could actually “catch” a civilization is pretty much when they are generating radio signals like our own AM and FM bands.
It makes sense for us to listen at those frequencies most of all, because when they get higher, more advanced tech, anything becomes possible, frequency jumping, etc.
AM and FM band frequencies are broadband radio transmissions, and they lack the watts of power necessary to be detectable beyond the edges of this Solar System even by the largest radio telescope receivers, such as the Arecibo radio telescope. Narrow band transmissions may be detectable by the largest receivers out to a distance of a little beyond a thousand lights years (LY), but only when the transmitters are broadcasting the narrow band transmissions with terawatts of power for a periods of time measured in the tens of thousands to millions of years necessary to travel through space to the Earth. Even if it is assumed there must have been millions of civilizations throughout just the Milky Way Galaxy alone, the number of such civilizations willing to transmit this much power for a long enough period of time to be detectable at the Earth at this particular time and distance from the transmitter likely remains quite small if any at all. So, the absence of a detectable radio signal from an alien civilization is no indication whatsoever that they do not exist.