This paper presents a novel compact self-quintuplexing antenna using a half-mode substrate-integrated waveguide cavity to implement multi-operation wireless services. The proposed antenna design incorporates five triangular protrusions of different dimensions, assembled with SIW to function as the radiating elements. Each radiator supports the one-eighth mode of the SIW cavity. The resonance frequencies of radiators are 3.63, 4.44, 5.23, 6.21, and 7.05 GHz. Each radiator operates at a distinct frequency due to the differing dimensions and is independently driven by 50 Ω microstrip lines. The measured reflection coefficients and isolation among any two ports are less than −10 dB and better than 23.6 dB, respectively. The measured gains at their respective resonant frequencies are 5.66, 4.84, 5.03, 7.08, and 6.59 dBi. The front-to-back ratio is better than 8.7 dB in each band. The difference of co-to-cross-polarization is greater than 19.3 dB.
