Research On Superfocusing And Crosstalk Suppressing Based On Spoof Surface Plasmon Polaritons

Spoof Surface Plasmon Polaritons(SSPPs) are electromagnetic waves propagating along periodically corrugated metal surfaces. In 2004, J. B. Pendry et al. proposed the concept of SSPPs, and then Hibbins et al. verified the existence of SSPPs in both microwave and THz regimes, opening up an avenue for the development and applications of SPPs in low frequencies.In this paper, some microwave devices based on SSPPs are proposed, including field strength enhancement device achieving high-efficiency guiding and focusing of SSPPs, high-performance low pass filter, and microstrip differential pair based on SSPPs improving the transmission performance of differential mode signal.Field strength enhancement device realizes momentum and impedance matching by using the gradient structure, and finally achieves a high-efficiency and broadband conversion between the guided wave and SSPPs. Numerical simulations of the proposed structure show that the amplitude of surface electric field at the conical endpoint is nearly 30 times higher than that of the feed from 10GHz~35GHz.By introducing symmetrically periodic grooves on both sides of the ground of the conventional CPW, the low pass filter has high band suppression in the stopband, and low insertion loss in the pass band. What's more, by introducing a periodic corrugated metallic strip with a defect unit on the back of the dielectric substrate, we can achieve a very narrow stopband in the working band of the low pass filter,and the frequency and suppression intensity of the narrow stopband have a good controllability.We apply the concept of SSPPs in the design of differential microstrip lines by introducing periodic subwavelength grooves on the edg of the microstrip lines. We can achieve effectively suppressing crosstalk and the conversion from differential mode signal to the common mode signal, reducing the far field radiation of electric field.