I think you're confusing three or four different projects at this point, whose only common property is that they operate on the energy of an incoming 2.4GHz signal (the "backscatter" thing).
The project that is the topic of discussion in this whole HN thread is the one that uses a 3D-printed plastic mechanism that changes the way an antenna (incidentally, 3D-printed too, out of a filament that mixes copper and plastic) reflects an incoming signal. There is a binary pattern, but it's encoded in the cog-like thing in the mechanism.
It's pretty much like sending light signals with a mirror, except it's reflecting radio waves. The way they use technical terms in this article (and the original paper) is problematic, and I believe your confusion in this subthread is a perfect example of why the abuse of "Wi-Fi" references is a problem.
I thought maybe I am missing something, but I see that the objects are encoded with bit and transmits.
Printed Wifi Paper
"PRINTED MAGLINK At a high level, by varying the magnetic properties of the material used within a single print job, we can embed multiple sequences of bits across the object. We consider the 3D printed object that modulates the magnetic field as the transmitter and the smartphone as the receiver.
Maybe it is the word modulates that is the issue?
Modulate Definition - In electronics and telecommunications, modulation is the process of varying one or more properties of a periodic waveform, called the carrier signal, with a modulating signal that typically contains information to be transmitted. Most radio systems in the 20th century used frequency modulation (FM) or amplitude modulation (AM) to make the carrier carry the radio broadcast. https://en.wikipedia.org/wiki/Modulation