A wideband and compact partial electromagnetic bandgap (PEBG) structure and a corresponding stopband-estimation model are proposed for the suppression of simultaneous switching noise (SSN) coupling in a multilayer printed circuit board. The proposed PEBG structure achieves a wide stopband with a compact size by adopting a geometric arrangement of patches that allows for a periodic narrow via pitch (NVP). In addition, the lumped capacitance model of the previously reported effective phase constant equation is replaced with the resonant cavity model to obtain the precise impedance of the patch in high frequency. Finally, it was successfully verified that, by applying the NVP-PEBG structure, wideband suppression of SSN coupling to the signal via is achieved with a bandwidth of 11.2 GHz below -40 dB. The proposed estimation model was validated through experimental measurements.