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The shielding properties of a rectangular enclosure with a doubly periodic array of apertures, exited by an obliquely incident and arbitrarily polarized plane wave is dealt with an improved method of moments (MOM) approach and mode-matching technique efficiently and accurately. Floquet waves for periodic structure are employed to represent the fields of the half-space, and the fields within the cavity are considered as superposition of waveguide modes. After enforcing the boundary conditions, MOM is used to obtain the shielding effectiveness and transmission coefficient. The proposed method has been successfully verified by a full-wave simulation tool CST and measurements. In our method, an arbitrary observation point is taken into account as well as higher order modes of the cavity. It is also found that all the resonant frequencies can be predicted from the transmission coefficient versus frequency curve. [ABSTRACT FROM PUBLISHER]

This paper proposes an improved thickness correction method for circuital models that can predict the shielding effectiveness analytically. This method considers the thick aperture as a short section of waveguide separating the two interfaces of its ends and treats only the dominant mode in this section. It is found that the improved correction method can generate more accurate shielding effectiveness than the traditional method. In all the examples, the accuracy of the results is validated by the transmission line modeling method. [ABSTRACT FROM AUTHOR]

An equivalent circuit model is developed to efficiently and accurately calculate the shielding effectiveness of an enclosure with an aperture. This model employs the concept of quasi-stationary admittance of diaphragms inside a rectangular waveguide and their equivalent circuits. The aperture is represented by a combination of a capacitive diaphragm, an inductive diaphragm, and step discontinuities inside a rectangular waveguide. This new model outperforms the existing circuit models in the following ways. First, it is more accurate compared to Robinson's model when the aperture is placed centrally (in height and width) in the front face of the enclosure. Second, it can deal with the aperture with arbitrary length–width ratio and arbitrary position. Third, it still works when the length of the aperture corresponds to an integer multiple of wavelength of free space radiation. While in such case the traditional circuit models are found to fail that the SE is erroneously predicted to be infinite. The proposed model provides a high degree of accuracy with a low computational burden, as compared with more complex numerical methods. In all the examples, the accuracy of the results is validated by results of transmission line modeling method and measurements if possible. [ABSTRACT FROM PUBLISHER]

It is known that in applying the time-domain methods to study electromagnetic response of the system, the long time record required for generating accurate frequency domain results can be extrapolated from a relatively short time record by using Prony's method. In this paper, the electromagnetic shielding performances of two highly resonant enclosures with slot or aperture array are investigated by a combination of the finite-element time-domain (FETD) and extended Prony's method with a much smaller number of iterations. The procedure and details of using this combined method to investigate the shielding properties of highly resonant enclosures is demonstrated extensively. Moreover, some rules about selecting the parameters such as sampling position, sampling interval, sampling duration, and number of poles are proposed. As shown by comparison with the direct FETD generated results, the combined method achieves the same type of accuracy of frequency-domain delivered power with a FETD time record computed over a much shorter time duration. [ABSTRACT FROM PUBLISHER]

The transmission-line modeling method and an analytical formulation are employed in this paper to investigate the electromagnetic shielding performance of enclosures with apertures. The effects of some related parameters, which are neglected in the formulation, are analyzed over a broad-band (0–3 GHz) to make the formulation optimal, and the shielding performance at some frequency points is studied in detail. Finally, approaches to improve shielding effectiveness are proposed. For the enclosures we studied, the theoretical analysis and simulation results illustrate that the analytical formulation can predict shielding effectiveness accurately when the frequency of the incident wave is less than 1 GHz, while when the frequency is more than 1 GHz, its applicability declines remarkably. Fortunately, the simulation results indicated that the shielding effectiveness can be improved to a certain extent by adjusting the spacing between apertures, selecting appropriate shapes of apertures, ensuring the longer side of apertures is not perpendicular to the polarization direction of the incident wave, and installing sensitive equipment according to the propagation direction in the case of that these properties of the incident wave are known. [ABSTRACT FROM AUTHOR]