In this work we present a stacked high-impedance surface (HIS) for low-profile, high-gain, 5 GHz WLAN antennas. The structure consists of two layers: a lower mushroom layer and an upper planar layer. We demonstrate that the stacked geometry has much better properties than conventional single-layer structures for achieving simultaneously surface-wave suppression and zero reflection phase at a given frequency. We show by measurements that the designed stacked HIS exhibits both a large band gap and in-phase wave reflection over the entire range from 4.6 GHz to 6.4 GHz. The structure is realized on FR4 substrate using standard etching technology to make fabrication easy and cheap
