A new symmetric feeding technique for a broadband series-fed antenna-array

In this paper, we present a new symmetric feeding technique for a broadband planar antenna-array. The antenna consists of four linear series-fed arrays of four microstrip patches positioned in parallel. To avoid any beam tilt during frequency scanning, one side of the array is supplied by a 0° signal whereas the same 180° out-of-phase signal feeds the other side of the array. A rat-race is especially designed to generate these two feeding signals. In comparison with other feeding techniques, there is no need to add some resistive load. To validate the concept, a 60 GHz prototype is designed and measured on Taclamplus substrate.