Broadband SIW Cavity-Backed Modified Dumbbell-Shaped Slot Antenna

Abstract

A cavity-backed modified dumbbell-shaped slot antenna based on a substrate integrated waveguide technology is proposed in this letter. Compared with the traditional dumbbell-shaped slot, the modified dumbbell-shaped slot not only introduces several new resonant points, but also makes the antenna obtain a higher gain. In addition, the high-order resonant modes (TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">102</sub> , TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">301</sub> , TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">302</sub> ) inside the subcavity are excited by the ground coplanar waveguide feeding structure, and the broadband impedance bandwidth can be achieved by making the high-order modes close to each other. The measured results show that the proposed antenna achieves an impedance bandwidth of 26.7% from 18.2 to 23.8 GHz and a peak gain of 9.5 dBi at 20.4 GHz. The cross-polarization levels of the antenna are around -40 dB at three measured frequencies.