Thanks OP, this is a nice resource.

One note, though. The presentation of IQ demodulation seems to mix up the real and imaginary components of the analytic signal with the electric and magnetic fields. Even if you skip the analytic signal and just generate a straight up real signal (with zero imaginary component), there will still be a magnetic field.

This seems important because the current presentation suggests the complex signal representation is somehow specific to electromagnetic signals, while it is really just a mathematical convenience applicable to any signal (EM, sound, wave on jump rope, etc).