In this article, a wideband substrate integrated waveguide (SIW) cavity-backed antenna with multi-resonance slots for Ku– band application is presented and experimentally investigated in terms of antenna performances including S-parameter, optimized parameter values, gain, and radiation pattern. With the proper placement of multi-resonant slots on the backside of the cavity, the hybrid modes are generate in the frequency band of interest. These modes can be tuned by varying the slot parameters which result the merging of different resonant frequencies, therefore the simulated impedance bandwidth is substantially enhanced to 1.46 GHz, ranging from 12.7 to 14.16 GHz with a gain of 6.0 to 8.0 dBi. The measured result showing the fractional bandwidth of the proposed antenna is 11.8% and 11% achieved at the resonant frequencies of 13 and 14 GHz, respectively. Moreover, the antenna has the features of simple-single layer structure, resonant frequency flexibility with multi-resonance characteristics over a wide impedance bandwidth. © 2017 Wiley Periodicals, Inc.