Broadband High-Gain Empty SIW Cavity-Backed Slot Antenna

To broaden the bandwidth of high-gain substrate-integrated waveguide (SIW) cavity-backed slot antennas, an empty SIW (ESIW) cavity-backed antenna with multiple high-order hybrid modes is proposed. Due to the ESIW configuration, the proposed antenna is independent on substrates and a high efficiency more than 90% in the operational band can be realized even the typical low-cost high-loss FR4 substrate is used. The proposed antenna has a wide measured bandwidth of 40.8% and the maximum measured realized gain can reach 11.1 dBi. The proposed broadband high-gain antenna can be used in radar and communication systems.