Switched-Beam Endfire Planar Array With Integrated 2-D Butler Matrix for 60 GHz Chip-to-Chip Space-Surface Wave Communications

A two-dimensional Butler matrix feed network is designed, implemented, and integrated with a 60 GHz 2 × 2 circular patch planar array for chip-to-chip communications. The realized antenna module is a thin multilayer microstrip structure with a footprint small enough to fit over a typical multicore chip. The network enables endfire (azimuthal) scan of the array main beam in the four diagonal directions, which is demonstrated for the first time in this letter. The antenna module provides a seamless and practical way to achieve reconfigurable interchip communication in multicore multichip (MCMC) systems. A hybrid space-surface wave interconnect is proposed that takes advantage of surface-wave coupling. The matrix is a four-input, four-output, i.e., 4 × 4, network consisting of four interconnected quadrature (90$^\circ$) hybrid couplers. A multiantenna module (MAM) consisting of five antenna modules that emulates diagonal interchip communication in MCMC systems is fabricated. The simulation and measurement of transmission coefficients between the antenna modules on the MAM are performed and compared.