“…The thermal motion of plasma of stars, the interaction of the EM waves with interstellar plasma and magnetic fields, the evaporation of primordial black holes [8], even ultra-high-intensity lasers [9] and other highenergy laboratory schemes [10,11,12] are possible means to generate the HFGWs in the GHz band and higher frequencies. Interaction of the HFGWs with the EM fields and the EM detection of the HFGWs have been theoretically and experimentally studied by many authors [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38].These works include the gravitation-EM conversion in the static EM fields(e.g., the Gertsenshtein effect and its inverse effect), the cavity classical-and cavity quantum-electrodynamical response to the HFGWs, resonant photon-graviton conversion, Barry's phase in the EM detection of the HFGWs, resonant interaction of the HFGWs with the EM wave beams, the rotation of the polarization vector of EM wave caused by the HFGWs in the toroidal waveguide, the difference frequency resonant response of coupled spherical cavities, etc.…”