A transformer can certainly be used for data transmission between two points and it uses a magnetic field for transmission. Real power is transferred but only the H field is used. You can separate the two windings so that the coupling factor is very small and still transmit power but the demands on the coils increase to preserve decent efficiency.
RFID tags (a lot of them) only use magnetic fields for transfer of data and power for the hand-held device.
But, the main trouble with using a H field (or a E field) is that it reduces in amplitude with distance cubed. A proper EM wave reduces the H (or E field) with distance i.e. no inverse cube or square law. Note also that the power of an EM wave reduces with distance squared because the power is proportional to E multiplied by H and if H and E halve with distance, the power quarters.
On the other hand every H field has an associated E field (maxwell etc..) so why do we say the H field reduces as per distance cubed - the reason is this - the H and E fields have to be of the correct ratio to constitute a bona fide EM wave. The ratio has to be the impedance of free-space (approximately 377 ohms resistive) so E is bigger than H by a ratio 377:1: -
When you plug the numbers into the equation, the square root of the ratio of permeability to permittivity is ~377 ohms.
With a simple oscillator and loop antenna (coil) running at too low a frequency, the E field will be too small to meet the above criteria and only a very tiny EM wave is produced. But, the H field is still "usable" for transferring power and data (inverse cube law) but the associated E field is of no use. When a loop is used that is dimensionally close to the wavelength of the carrier frequency, the E field rises and a properly proportioned EM wave is produced. This is what we call a radio wave - it has electric and magnetic parts at a ratio of 377:1.
Regards the use of a H field to free-up bandwidth (Q2) - this will interfere with an EM transmission if at the same frequency - there is no magic bullet on this - interfere with the E or the H fields from another source and you'll disrupt the ability of a receiver to detect the original EM wave. The energy returned is not identical to the energy sent/stored if energy is removed. Energy has to be removed by a receiver or it receives nothing.
The article linked is profoundly incorrect when it states this: -
It is my belief that radio waves are nothing more than a simple
The article also said this: -
A complete circuit is just plain not necessary
Of course a circuit is necessary and although a whip antenna may look incomplete the capacitance to to return wire (earth in the case of a quarter wave antenna) completes the circuit. No complete circuit = no current flow = nothing.