A Spoof Surface Plasmon Polaritons Frequency Scanning Antenna Based on Coplanar Waveguides

In this paper, a novel spoof surface plasmon polaritons frequency scanning antenna is proposed. A specific periodic structure in the substrate integrated waveguide (SIW) is constructed to realize the surface wave with the characteristics of surface plasmon dispersion similar to those of optical band. An impedance transition structure is then designed to gradually convert a spatially-guided wave in the coplanar waveguide into a surface wave mode in the groove periodic structure. The surface wave is a slow wave and does not have a leakage emission, so a periodic modulation is needed to produce leakage-radiation characteristics. By constructing the cosine periodic groove on the inner conductor of the surface-wave transmission line based on the SIW, the surface wave can be transformed into a space wave so that the frequency-sweeping characteristics of the leakage wave antenna with a directional pattern can be realized. Simulation results show that the antenna can achieve a bidirectional scanning range from −16° to 65° over a frequency band of 4 – 8 GHz, and the maximum gain is 13 dBi. Also, the periodic modulation structure is embedded in the inner conductor part of the coplanar waveguide, so it is simple and easy to be integrated.