A low-profile cavity-based self-quadruplexing antenna (SQA) is projected by using substrate-integrated waveguide (SIW) technology for multiband wireless communications. Four quarter-mode-like SIW-based cavity resonators are used for radiation and each resonator is fed individually by four distinct printed feed lines. The proposed antenna topology offers four resonant frequencies around 3.5, 5.2, 5.5, and 5.8 GHz band when excited by the corresponding feed. By appropriately adjusting the design essentials, an isolation around 23.6 dB is realized between any two input ports. Thus, four separate signals can coexist on a single antenna assembly without interfering each other, which help to realize the self-quadruplexing phenomenon. Finally, the antenna is prototyped and experimentally verified. The experimental results show good agreement with simulated counterparts. Moreover, the proposed design retains the advantages of a small footprint, compact size, low cost, and ease of manufacturing, which makes it a promising candidate for highly integrated handheld transceivers. © 2019 Wiley Periodicals, Inc.