A tri-band shared-aperture antenna with a scanning beam for the sub-6 GHz and millimeter-wave applications

A tri-band shared-aperture antenna for Sub-6 GHz/millimeter-wave (mmWave) applications with a scanning beam is proposed. Using structural multiplexing, the dual-band Sub-6 GHz mesh patch antenna and the millimeter-wave (mmWave) Fabry-Perot cavity antenna (FPCA) share the same radiating aperture. The metal mesh patch acts as both the radiator of the dual-band mesh patch antenna and the partial reflective surface (PRS) of the FPCA. The mechanism of the FPCA is analyzed using the ray tracing method. With the designed single-layer PRS, the proposed antenna features a scanning beam in the mmWave band without the need for tuning elements and feeding networks. An aperture-coupled patch antenna is designed as the feed source for the FPCA. Additionally, by optimally shaping the metal mesh, the patch antenna generates dual-band resonances. The antenna prototype is fabricated and measured. Measured results show that the impedance bandwidth of the antenna is 2.07% (2.39 - 2.44 GHz), 24.79% (3.18 - 4.08 GHz), and 28.42% (24.90 - 33.15 GHz), respectively. The tri-band peak gains are 8.18 dBi, 8.39 dBi, and 17.41 dBi, respectively. The beam scans from 2 degrees to 39 degrees in the frequency range of 25 - 33 GHz.