We provide a detailed characterization of the transmittance properties of subwavelength slit apertures on Ag and Au plates, as a function of the slit width and plate thickness, for frequencies ranging from 1.2 to 500 THz. As the method of analysis, we choose a mode-matching technique incorporating both discrete and continuum spectra because of its accuracy and suitability to this geometry. The transmittance behavior is shown to be strongly impacted by the variability of the electromagnetic bulk properties of Ag and Au across the terahertz range. The results obtained here constitute a useful compendium of reference data for subwavelength slit transmittances on metal plates at terahertz frequencies.

this paper proposes the hybrid Vivaldi-fed horn antenna, which consists of the printed AVA on a FR4 substrate for better matching performance in the low frequency band and the horn antenna that surrounds the exterior of the AVA for increased gain performance in the high frequency. In order to verify the operating principle in the low frequency band, an equivalent circuit of the proposed antenna is modeled and analyzed. The mode decomposition technique is then used to examine the radiation physics of the proposed antenna in high frequency band. The measured reflection coefficients in the entire frequency range are less than –3 dB of the half power reference (maximum of –4.11 dB). The measured gains of 2.12 dBi at 1 GHz and 7.84 dBi at 6 GHz are obtained. These results confirm that the better characteristics in low frequency matching and high frequency gain can be achieved by the proposed design.

This article investigates the electromagnetic field strengths and the resulting indoor exclusion zones (EZs), taking into account the actual indoor nuclear power plant (NPP) environment. To obtain the accurate indoor EZ, a real indoor environment based on the simulator room of Korea Institute of Nuclear Safety was included in the numerical simulation. The maximum distance d of the indoor EZs depending on the position and polarization of the emitter is 1 to 2.1 times longer than the distances d of the free-space EZs. To validate the simulated indoor EZs, electromagnetic field strengths along the arc line with an arbitrary distance from the emitter are measured in the NPP, which are in good agreement with the simulation results. The result demonstrates that the indoor EZ should be investigated before applying the wireless system in the NPP because the indoor EZ and free space EZ can be significantly different.

This paper presents an analytical interpretation of electromagnetic interference between solid-bottom type open cable trays in a nuclear power plant under the assumption that an electric-line current is undesirably generated from a damaged cable in an open cable tray. Based on the superposition principle and Helmholtz’s equation in conjunction with the separation of variables, we employ a mode-matching method to obtain analytical solutions to the postulated electromagnetic interference problem. Before conducting a mode-matching analysis, we investigate the radiating principle of the electric field interfering with a victim cable tray by deriving the array factor in consideration of an imaginary electric-line current. In addition, we characterize the electric fields with a propagating mode at an observation point in the victim cable tray using the derived expression of the electric field. Based on this, we validate the formulation and computation of our mode-matching method and then computationally investigate the strength and distribution of interfering electric fields in terms of the separation distances provided in regulatory guidance on the electrical independence of a nuclear power plant. Finally, we compute the strength and distribution of the interfering electric field at the observation point when the location of an electric-line current is modified. The results of the study provide us with the useful information to alleviate the electromagnetic interference between open cable trays in a nuclear power plant.

This article investigates the scattering characteristics of periodic open cabinets in nuclear power plants using the mode matching technique. The concept of a parallel plate waveguide is adopted, and the power conservations at all junctions are confirmed. The incident power is almost equivalent to the summations of the reflected and transmitted powers at all junctions, and the differences in power for all cases are almost zero. A multiregion problem is systematically applied to resolve the entire scattered fields, and the resulting contour plots for the field strength according to various modal incidences are displayed. Based on this study, modal field distributions for multilayer cabinet structures can be extensively analyzed.

This article investigates the resonant transmission characteristics of periodic subwavelength slits on real metallic plates at terahertz frequencies. By applying the eigenvalues of the slit to the mode matching technique (MMT), the transmission characteristics of the periodic subwavelength slits can be resolved as function of the gap width, plate thickness, and frequency. The resulting transmittance of the proposed method is then verified by comparing it with a commercial electromagnetic simulation software. This study demonstrates that the proposed MMT is suitable for calculating the transmittance of the periodic metal-insulator- metal slits on the real metal material and provides in-depth intuition for resonance phenomena using the modal approach.