Low-Profile Metasurface-Based Diaphragm for Compartment Shielding of Microwave Cavities

Abstract

This article proposes several low-profile metasurface-based compartment shielding diaphragms for the high-speed and highly integrated circuits located in the space-limited cavities. It was demonstrated that the capacitive metasurface (CMS) and inductive metasurface (IMS) partially filled in the cross section of cavities can generate new transverse electric and magnetic resonance modes, which are orthogonal to the TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> mode of the cavity. Benefitting from the mode-mismatch between the transverse electric/magnetic resonance modes and the TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> mode, a large shielding effectiveness (SE) can be obtained. It is found that, even when the metasurfaces are designed with a low profile (the ratio between the metasurfaces' profile and the cavity's height h/h <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> <; 0.5), they can introduce a large SE at a desired frequency band, which is deemed difficult to achieve by utilizing conventional waveguide diaphragms with such a profile. Moreover, the CMS and IMS can be aligned as a complementary metasurface (CPMS) to enhance the working bandwidth significantly, by elaborately designing their surface impedances. The CMS, IMS, and CPMS samples with a thickness less than 0.1λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> and a profile less than 0.15λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> , i.e., less than one-third of the cavity's height, were fabricated and tested in a compartment scenario, respectively. The developed technique is validated by the good agreement between the simulation and measurement results. The low-profile shielding diaphragms reported in this work can provide the effective solutions in many compartment shielding scenarios, such as integrated radio frequency (RF) modules and system-on-chip (SoC) packages.