what is this !radiant! energy?
In dense aether model the space-time is formed with foamy fluctuations of aether (false vacuum). This foam can mediate energy in two ways: in transverse waves of light along the walls of its bubbles and in longitudinal waves - so called scalar waves - which result from compression of the cells of this foam. Their dual counterpart is the A-field at the center or toroid coil, whereas the normal magnetic field remains constrained around it as a normal B-field. The analogy of this dual wave spreading are surface and underwater (sound) waves in the water. The sound waves are weaker, but much faster than the surface waves. This analogy enables to understand many aspects of scalar wave formation and propagation rather easily.
In classical electrodynamics of Maxwell the spherical antenna cannot radiate, only less or more elongated dipole rod can. But Nicola Tesla, Eric Dollard, Konstantin Meyl and another physicists demonstrated repeatedly, that the spherical antenna or capacitor (also bifilar and caduceus coil forming such a capacitors internally) can also exchange charge at distance during brief pulses and that these pulses form a compression waves of vacuum, which propagate in superluminal speed. I.e. not with normal sheer waves of light which can be polarized - but via scalar waves.
Therefore if we introduce a high voltage pulse into some conductive device, then it generates a compression wave around itself radiated from every piece of its surface into outside like the glowing cathode of neon tube: a radiant energy! Even single wire is able to mediate energy at distance after than, as Nelson Rocha also demonstrates in his videos. Other than that, the scalar waves are doing everything in opposite way, than the normal light waves, being orthogonal to them within hidden extradimensions of vacuum. They actually don't manifest itself like normal waves, but like less or more indeterministic noise or streamers of fluctuations and they don't undergo polarization, refraction and diffraction.
The normal and scalar EM waves usually come together, every photon is a tiny piece Maxwell wave stuffed with scalar component like soliton. If this component wouldn't be present there, then the photons would be indistinguishable from normal Maxwell waves, which cannot be counted. In general, the scalar waves are not formed (only) when the electric field alternates - they're formed during electric pulses and spikes instead, when the electric field changes its intensity instead of just polarity. In harmonically undulating circuits the scalar wave generation remains suppressed instead and it evades attention. The scalar waves don't radiate and spread in spherical envelope, but they form a nondispersive beams (warp field), which remember the shape of their radiator and which exhibit a mechanical effects and sensations at distance. In many situation, especially under higher energies they propagate through vacuum rather like the very-lightweight particles: magnetic turbulence and vortex rings of vacuum. The neutrinos are collapsed solitons of these waves in similar way, like the photons are solitons of normal EM waves. The analogy with Falaco and Russel solitons at the water surface comes on mind here.
The scalar waves are not absorbed with metals with freely movable electrons, so that they cannot be shielded with Faraday cage and this property can be used for their effective separation from normal EM wave, because - as follows from above examples - the scalar waves always follow normal EM wave generation and vice-versa. You therefore cannot generate a scalar waves in their pure form with normal oscillating circuit, as these waves will be always contaminated with normal EM waves. Instead of it the scalar waves are absorbed and radiated with materials, in which electrons cannot move freely, but their motion remains constrained in one or two dimensions: superconductors and topological insulators, like the graphene (but not graphite). Also the common ferromagnets can shield and radiate scalar waves, once they're arranged in monopole arrangement, of ferrites can radiate them during fast changes of their saturation. This is IMO the primary source of scalar waves in Nelson Rocha circuit.
The scalar wave physics looks counterintuitive only when we have no deeper mechanical models of vacuum on mind. The simplified Maxwell model of vacuum cannot describe / predict them, but once we imagine the vacuum like any other elastic continuum, then they can be actually understood quite easily. Whole the quantum mechanics would be unthinkable without these density waves at all, because the scalar component of field is the source of quantum fluctuations and uncertainty. Therefore the physicists are already dealing with scalar waves a long time before they admitted their existence - they just named them differently: quantum fluctuations or virtual particles of vacuum, CMB noise, ZPE field, Casimir field, warp field, evanescent waves, N-rays, axions, dark matter particles and another similar closely related stuffs.