Miniaturized, Multilayer, Shielded, and Surface-Mountable 5G N79 Bandpass Filter

This paper presents miniaturized fourth-order bandpass filter (BPF) design with proposed shielded meandering resonators based on multilayer printed circuit (PCB) technology. Shielded inside a substrate integrated waveguide (SIW) cavity, the proposed meandering resonator achieves miniaturization by introducing inter-coil and additional coil-to-ground capacitances. Fourth-order bandpass response is realized by arranging shielded resonators in a 3-D configuration. Square slot etched on middle ground plane is introduced to achieve controllable electric coupling in vertical dimension. Two transmission zeros are designed on both sides of the passband, leading to a sharp skirt characteristic. This surface-mountable filter for 5G N79 band occupies a relatively small size of 7.8×5.79×1.406 mm
³
(0.12×0.088×0.021 λ
0
³
).