A High Aperture Efficiency Endfire Antenna Based on Spoof Surface Plasmon Polaritons

Abstract

A high aperture efficiency endfire antenna based on odd mode spoof surface plasmon polaritons (SSPPs) is proposed in this article. First, a pair of symmetrical SSPPs transmission lines (TLs) is applied to an endfire antenna. To realize an endfire antenna, the SSPPs TLs are supported by a balun with a 180° phase shifter, and this makes each pair of SSPPs units works as a dipole. Next, we study the dispersive curve of this dipole-shaped SSPPs unit and get its relationship between phase constant and frequency. Then, the Hansen–Woodyard condition is used to get a maximum gain at endfire direction. Moreover, in order to excite a radiation into the free space, we compose a tapered structure with this pair of SSPPs TLs. As a result, an endfire antenna with zero tilted angle operates in the frequency range of 9–11 GHz and achieves an average gain of 11.51 dBi. In addition, this SSPPs antenna realizes a high aperture efficiency up to 13.26 dBi <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$/\lambda _{0}^{2}$ </tex-math></inline-formula> . The simulated and measured results are in good agreements over the operating band. The proposed SSPPs endfire antenna holds a low profile, small aperture, and it is promising for application in satellite and radar communication systems.