Wifi didn't exist when Voyager was launched...
If the frequency is high enough then the waves of light can be detected by things as small as cells in the back of your eye, or the pixels in a camera sensor. If it is too low then you need much larger detectors.
Other animals have detectors for different frequencies/wavelengths, allowing them to see either infra-red (mosquitos) or ultraviolet (bees, butterflies etc).
What we call "visible light" is just the particular range that our eyes can detect (about 400 to 800THz). If we were the size of a planet, and our eye cells were the size of a radio-telescope dish we would be able to "see" in those wavelengths. In fact, when we see images taken by radio telescopes, those have been essentially pitch-shifted up to something we can see, like the reverse of what we do when listening for bat clicks (where the pitch is downshifted to our hearing range).
The wikipedia article has a nice little diagram putting the wavelengths into perspective. https://en.wikipedia.org/wiki/Electromagnetic_spectrum
This makes me think of the dual slit experiment. Does the universe treat everything as a wave to save CPU cycles or something?
If we think of light as little balls (at our size i think that would make sense). If we were much bigger, we would think of these longer waves as balls too?
One way of thinking of it - everything is a wave until you make a measurement. Then you get a "collapse" (localization) of the wavefunction. Which leads to the question of why the wave function collapses - i.e. how does nature know we want to make a measurement.
Which leads to all sorts of crazy ideas like the simulation hypothesis. Which is not a scientific theory, because you can't falsify it, but even very educated people like Neil DeGrasse Tyson have remarked on it.
In addition to it being 2.4GHz, this is the reason for having the National Radio Quiet Zone near Green Bank