Wideband Millimeter-Wave Antenna With Low Cross Polarization Based on Spoof Surface Plasmon Polaritons

A novel wideband millimeter-wave antenna with low cross polarization based on spoof surface plasmon polaritons (SPPs) is proposed in this letter. Periodic metallic grooves operate as an SPP transmission line with high electromagnetic field confinement. The concept of dielectric tapered rod antenna is employed to design an SPP rod antenna with linear-tapered groove depth, converting the confined energy to radiation mode. Meanwhile, the tapered structure only affects the E
_z
component on the transverse plane, and thus it can achieve low cross polarization. This prototype is fabricated by three-dimensional printing technique and surface metallization process. The radiating length of the linear-tapered SPP antenna is 29.2 mm, and the measured |S
₁₁
| is below -15.6 dB from 50 to 75 GHz. Experimental results show that the linear-tapered antenna can achieve an average gain of 14.95 dBi with ±1.45 dBi variation and better than -25.6 dB cross-polarization level for E-plane radiation.