Reduction of Shielding-Box Volume Using SPP-Like Transmission Lines

To overcome the problem of external disturbance, the shielding-box technology is widely used in most modern electrical circuits and systems, especially at high frequencies. However, for traditional microwave planar transmission lines (TLs), it is very difficult to reduce the volume of the shielding box because of the potential interference between the shielding box and propagating electromagnetic (EM) fields. Here, based on the tight field confinements of surface plasmon polaritons (SPPs), we propose a method to reduce the shielding-box volume from the physical point of view. We demonstrate theoretically and experimentally that the EM signals on planar SPP TLs have better propagation performance than those on traditional microstrip lines with the same size and separation to the shielding box. Hence, we achieve a compact shielding box and provide a potential solution to improve the packaging technologies.