Dual-band spoof surface plasmon polaritons based on composite-periodic gratings

We propose a composite grating structure constructed by a double-periodic groove array with finite thickness, which supports two tightly bound spoof surface plasmon polaritons (SPPs) at two frequency bands. The two SPP waves correspond to the dominant modes of two single-periodic gratings with different groove depths, and the cutoff frequency of each mode is determined independently by the individual groove depth. We design and fabricate the dual-band SPP waveguide in the microwave frequency, and the measurement results show good performance of SPP propagations. The ability to guide two independent-band SPP waves could be important for developing novel surface wave devices.