To go over it a bit more: the higher the frequency of radiation the smaller you can make the antenna. However in the frequencies we have the technology to send signals in, and don't intrinsically give you cancer, everything becomes more opaque when you increase frequency. As OP says, it's like trying to send a light flash from behind a concrete wall, when you can see it on the other side you're using enough energy to vaporise the concrete anyway.
This is basically the only reason why we aren't living in a surveillance dystopia to make the Matrix look tame. Thank you physics for limiting the amount of possible surveillance from smart dust.
That said, you could still use chemical or physical means of communicating with microchips inside you, the issue is that you're very limited in how much information you can send without having them come in contact with some type of macroscopic io device.
https://en.wikipedia.org/wiki/Dipole_antenna
To go over it a bit more: the higher the frequency of radiation the smaller you can make the antenna. However in the frequencies we have the technology to send signals in, and don't intrinsically give you cancer, everything becomes more opaque when you increase frequency. As OP says, it's like trying to send a light flash from behind a concrete wall, when you can see it on the other side you're using enough energy to vaporise the concrete anyway.
This is basically the only reason why we aren't living in a surveillance dystopia to make the Matrix look tame. Thank you physics for limiting the amount of possible surveillance from smart dust.
That said, you could still use chemical or physical means of communicating with microchips inside you, the issue is that you're very limited in how much information you can send without having them come in contact with some type of macroscopic io device.