Broadband SIW Cavity-Backed Novel Slot Antenna With a Shorting-Via for Ka-Band Applications

A cavity-backed slot antenna for airborne broadband Ka-band applications based on Substrate Integrated Waveguide (SIW) technology is proposed in this paper. The antenna features a novel slot with a shorting-via and is fed through a coplanar waveguide, resulting in good bandwidth and gain. The antenna is excited by the TE310 mode, TE130 mode, and the hybrid mode of TE310 and TE120 mode in the cavity, leading to resonant frequencies that are close to each other, thereby enhancing the impedance bandwidth. A prototype was fabricated and measured. The measurement results show that the antenna operates at 27.58-32.71 GHz, with an absolute bandwidth of 5.13 GHz, the relative bandwidth of 17.02%. The peak gain of the antenna reaches 11.5 dBi. Compared with the traditional designs, such as rectangular or simple slots with shorting-vias, the proposed antenna achieves varying degrees of improvement in both relative bandwidth and gain. The antenna features a compact size (14 mm $\times 12.8$ mm $\times 0.787$ mm), wide bandwidth, high gain, and low profile. It is well-suited for broadband Ka-band applications.