A Butler Matrix Based Multi-beam Antenna Array Fed by GSG Probe in W-band

In this paper, a multi-beam ridged waveguide (RWG) slot antenna array is introduced. The antenna consists of four components: four ground-signal-ground (GSG) ports, a micro-coaxial line (CL) Butler matrix beamforming network (BFN), four CL-to-RWG transitions, and a 4 × 1 slot RWG antenna array. The GSG ports allow electromagnetic energy to be fed to the antenna through GSG probes, facilitating measurement and applications. The Butler matrix has four ports and, when individually fed at each port, provides a phase gradient of ±45 and ±135 degrees for the subsequent antenna array, enabling beam scanning of the antenna. The CL-to-RWG transitions achieve impedance matching and mode conversion with low insertion loss between the TEM wave from the micro-CL and the quasi-TEM wave in the RWG. The 4 × 1 slot RWG antenna array realizes radiation with high efficiency and high gain. Operating in W-band, the antenna array necessitate compact dimensions and precise fabrication. To fulfill these requirements, we plan to utilize the micro metal additive manufacturing (M-MAM) technology for fabrication. M-MAM, distinguished by its 5-layer full-metal stack design, represents an advanced technology known for its low loss, unparalleled precision, and efficiency. And the proposed antenna design meets the fabrication requirements of M-MAM technology. The simulated results emphasize the capability of the proposed antenna arrays, operating at 100 GHz, to achieve beam-scanning ranges of ±57°, accompanied by maximum gains reaching 8.6 dBi, with a −10 dB impedance bandwidth from 95 to 105 GHz. The considerable beam-scanning range and high operating bandwidth make the proposed antenna array a novel choice for W-band multi-beam antenna applications.