Among them, there had been some valuable works on subwavelength corrugated structures which can be used to transmit spoof SPPs 9, 10, 11, 12, 13. The plasmonic metamaterials are usually formed by one- or two-dimensional periodical textures on metal surfaces. In order to realize SPPs in such lower frequencies, plasmonic metamaterials have been proposed to produce the so-called spoof SPPs 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14. However, the metals will behave like perfectly electric conductors (PECs) instead of plasmas with negative permittivity when the frequency is reduced to the terahertz and microwave bands, which do not support the existence of SPPs. The proposed structure can be used as an SPP filter with good performance of low loss, high transmission and wide bandwidth in the selective frequency band.īecause of the negative permittivity behavior of metals at visible frequencies, surface plasmon polaritons (SPPs) are propagating on the interface of metal and dielectric with exponential decay in the direction vertical to the interface 1, 2. The measurement results show that the reflection coefficient is less than -10 dB with the transmission loss around 1.5 dB in the selective frequency band from 7 to 10 GHz, which are in good agreements with numerical simulations.
We fabricate and measure the frequency-selective spoof SPP structure in microwave frequencies.
To make a smooth conversion between the spatial modes in CPW and SPP modes, two transition sections are also designed. The structure is fed by a traditional coplanar waveguide (CPW). Designed on a thin dielectric substrate, the ultrathin metallic structure is composed of two oppositely oriented single-side corrugated strips, which are coupled to two double-side corrugated strips. We propose an ultrathin metallic structure to produce frequency-selective spoof surface plasmon polaritons (SPPs) in the microwave and terahertz frequencies.
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