Bandpass Shielding Enclosure Design Using Multipole-Slot Arrays for Modern Portable Digital Devices

In this paper, we reveal a design approach for a bandpass shielding enclosure (BPSE) that uses multipole-slot arrays applicable to modern portable digital devices having wireless communication functions. The BPSE is a conductive, airtight box etched with the apertures of a periodic multipole-slot array on its top and bottom surfaces. The BPSE is designed to achieve the design objectives of high transmittance in the specified wireless-signal band and high shielding effectiveness outside this band, and to have little influence on the radiation characteristics of an internal antenna located inside the enclosure. Three representative kinds of multipole-slot arrays: slot arrays, tripole-slot arrays, and cross-slot arrays, were considered in this study. In addition, these arrays may or may not have end loading. A prototype of the BPSE was created and studied. Simulated and measured results were obtained to validate the design. Based on these results, a detailed performance comparison among all the considered arrays is given. The comparison demonstrated that only the BPSE with a cross-slot array and full end loading can simultaneously meet all the design objectives.