A self-multiplexing SIW antenna based on hexagonal SIW cavity is proposed. The structure consists of resonating elements of different sizes, which provide the hexaband operations. The antenna resonates at 5 GHz, 5.17 GHz, 5.32 GHz, 5.53 GHz, 5.62 GHz, and 5.72 GHz by employing different slot lengths between the resonating elements. The antenna geometry is arranged so that independent tuning of individual operating frequencies is possible without affecting the remaining center frequencies. The selfhexaplexing antenna exhibits a port isolation better than 29 dB between the resonating elements with a low frequency ratio of 1.14. The simulated gain of the antenna is 5.32 dBi, 5.68 dBi, 5.41 dBi, 5.91 dBi, 5.43 dBi and 5.14 dBi at the respective operating frequencies. The proposed self-hexaplexer operates in the NR band (n46) therefore being suitable for communication system applications.INDEX TERMS Substrate-integrated waveguide, frequency ratio, isolation, self-hexaplexing antenna, tunability.