Spoof Surface Plasmon Polaritons Fed Frequency-Scanning Open-Loop Antenna Arrays

Spoof surface plasmon polaritons (SSPPs) fed open-loop elements without a metallic ground plane are investigated for the SSPPs-based antenna design. By employing a straight SSPPs section close to the open end of the loop as the feed, the one-wavelength and one-and-a-half-wavelength modes of the open-loop are excited effectively, which can generate radiation fields with orthogonal polarizations. Based on the open-loop arrays operating in different modes, two Ka-band SSPPs-fed leaky-wave antennas with frequency-scanning in the H- or E- plane are then designed, fabricated and measured. Wide impedance bandwidths, stable gain of around 13 dBi and radiation efficiency of higher than 70% are confirmed experimentally. The studies in this letter provide a new means to adjust the polarization features of the SSPPs-fed antennas. Benefitted from the compact single-layered geometry that is easy to integrate with circuits and good radiation performance, the proposed SSPPs-fed antenna arrays would be an attractive candidate for future millimeter-wave wireless applications.