Reduction of Electromagnetic Noise Coupling to Antennas in Metal-Framed Smartphones Using Ferrite Sheets and Multi-Via EBG Structures

Recent smartphones increasingly employ a metal frame for a sophisticated design. However, the metal frame becomes a good coupling path for electromagnetic (EM) noise within smartphones and increases noise coupling to radio-frequency antennas located at the top and bottom sides of the smartphones. This paper proposes two novel metal frame structures with ferrite absorbing sheets or electromagnetic band gap patterns to reduce the coupling of EM noise to the antenna. Using a fabricated test board, the effects of the proposed metal frames on noise coupling suppression are experimentally validated.