Half-Mode Substrate Integrated Waveguide Dispersion Tailoring Using 2.5-D Spoof Surface Plasmon Polaritons Structure

In this article, a half-mode substrate integrated waveguide (HMSIW) combined with 2.5-D spoof surface plasmon polaritons (SPPs) structure is proposed to tailor the dispersion features and cutoff frequency of the HMSIW. The proposed HMSIW-SPP structure has a smaller longitudinal dimension since the dispersion of the proposed structure can be tailored by adjusting the geometric parameters of the 2.5-D spoof SPP arbitrary. Simultaneously, the proposed structure has a smaller lateral width than that of the classical HMSIW because the 2.5-D spoof SPP introduces extra capacitance in the waveguide. Moreover, an equivalent circuit model is proposed and used to analyze the design principles. The structure exhibiting the cutoff frequency of 6.0 GHz is designed and fabricated under the printed circuit board process. Measurement and simulation results show that the proposed HMSIW-SPP structure decreases the longitudinal dimension by more than 50% and the lateral width by 25% without sacrificing its transmission performance. Due to the reduced cutoff frequency and effective wavelength, the proposed structure enables extreme miniaturization and can be applied in the design of miniaturized microwave circuits.