Compact millimeter-wave switched-beam antenna arrays for short range communications

The need for more data throughput is a requirement that will keep growing in future wireless standards, and during the past few years, millimeter-wave technology has generated much excitement in the mobile and wireless communications sectors due to the large bandwidth it can offer. In this letter two different travelling-wave, slot antenna arrays are proposed which can offer tunable switched-beam capability at millimeter-wave frequencies. The antenna systems are built on a single layer PCB with top- and bottom-side etching for operation at 28 GHz with at least 0.7 GHz of measured impedance bandwidth. For the first design, a planar 2 × 4 slot antenna array is proposed while the second design is implemented using a 4 × 4 slot array to demonstrate improved beam directivity. A Butler matrix for simple beam switching in the far-field is also integrated within the compact antenna structure to provide the needed phased array operation. The total size of the two proposed systems with their feed networks are 55.2 × 55 × 0.13 mm³ and 53.7 × 61.2 × 0.13 mm³, respectively. These new travelling-wave switched beam arrays can be placed within current handheld mobile devices for high bandwidth short range communications enabling 5G technologies.