There are two types of radio frequency heating:the induction heating for the electrically conducting materials such as metals and metal like materials where the material to be heated is put in the center of a heating coil. When rf current is passing through the coil it generates magnetic field which intercepts the material and generates in it an electromotive force by induction. This electromotive force drives eddy currents in the material leading to converting it into heat in the electric resistance of the material.

The other type of radio frequency heating is the dielectric heating where the rapidly varying electric field applied on the dielectric material will cause the material dipoles to move accordingly. At sufficiently low frequency the dipoles can follow the electric field variations and the dielectric losses will be negligible. At sufficiently high electric field the dipoles will lag behind the electric field causing electrical losses. This type of losses is called the polarization losses. The polarization losses peaks at specific frequencies of the applied electric field depending on the type of polarization.

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External EM fields can accelerate the charged particles in a substance, which could raise its heat energy if the substance can absorb the EM field energy. It seems that the substance must have electric dipole molecules in order to absorb EM energy in the RF range. Dipole molecules absorb the RF EM energy by a rotation motion initially, that is translated into linear random motion of all the molecules in the substance (or to a higher phonon energy in solid substances) by means of the "intermolecular dynamics". That is why you should not press your smartphone against your ear too long, this heats your head and damages your skin cells, since the H2O molecules in your cells are dipoles, not to mention the possibility that RF signals disturb signals in the nerve system. Better to activate the loudspeaker in your phone.

I'm conducting a research were the heat generated by a Poisson based RF signal should be lower than a sinusoidal signal with the same intensity. What theory could explain this?

the targeted material is tissue which I presume has insulating effects.