Metallic-Waveguide-Fed and Low-Sidelobe mmW Endfire Antenna Based on SSPP

This letter addresses the antenna challenges faced in corridor-like environments in the IoT world. High-gain and large-bandwidth antenna with fixed beam is required and the spoof surface plasmon polariton (SSPP)-based mmW end-fire antenna fits the requirement perfectly. Few SSPP mmW antennas have been reported, and most of the existing SSPP antennas are fed by SMA and fabricated by PCB. Considering that metallic waveguide is the most important feeding interface and dielectric loss severely degrades antenna efficiency at mmW band, this letter proposes a metallic-waveguide-fed SSPP-based end-fire antenna at 60 GHz. A sword-shaped grooved copper rod is inserted into a metallic waveguide to form proposed antenna. The tapered handle penetrates into the trapezoidal matching air cavity for wideband matching. The grooves are tapered to achieve high end-fire gain and low sidelobes (SLLs). The CNC-machined prototype verified the design strategy. The measured results show that the -10 dB impedance bandwidth is basically 45.6∼>67 GHz and within 55∼65 GHz, the end-fire gains are 12.1∼15.6 dBi and the SLLs are better than -17.1 and -21.1 dB in E- and H-planes, respectively. This letter also proposes a new concept for designing mmW antennas by simply inserting a customized radiator into an open waveguide.