In this article, a new method to enhance the impedance bandwidth of a squareshaped substrate integrated waveguide (SIW) cavity-backed slot antenna is presented. Using perturbation technique by two corners cuts along two opposite sides of the cavity's diameter, the two degenerate TE120 and TE210 modes of the cavity are separated and a wideband SIW cavity-backed slot antenna is developed. A parametric study is carried out to study the effects of the shape of the perturbation on the radiation performance of the introduced antenna. The proposed antenna is simulated using full-wave software and a prototype of the antenna is fabricated to investigate experimentally. It is shown that the measured results agree well with those obtained by simulation. The measured results show that the designed antenna offers 5.7% fractional impedance bandwidth with a peak gain of 6.4 dBi, while provides a few advantages including low profile, light weight, easy fabrication with low-cost printed circuit board (PCB) and convenient integration with planar circuits. The introduced antenna can be used as a single antenna or as an element of a large antenna array.

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