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Hybrid Electromagnetic Boundary for Cavity Resonance Suppression

In order to improve the traditional packaging techniques, a perfect electric conductor-perfect magnetic conductor (PEC-PMC) hybrid boundary scheme is proposed to suppress the resonant frequency of a closed metal cavity in this paper. An analytical formula of the resonant frequency of the PEC-PMC hybrid cavity is derived and then extended to cylindrical cavity with an arbitrary cross section. The simulation results indicate the accuracy of the formula. The lowest resonant frequency of the original PEC cavity is greatly increased and pushed outside of the working band by adding the PMC on its top surface. Finally, it is proposed to construct an artificial PMC boundary by covering a mushroom-type high impedance surface (HIS) on the surface of the cavity. The simulation results indicate that the mushroom can suppress the resonance frequency.