Broadband SIW Cavity-Backed Slot Antenna for Endfire Applications

A broadband substrate integrated waveguide (SIW) cavity-backed slot antenna for endfire applications is presented in the letter. The antenna employs a semiclosed SIW cavity with one sidewall removed and two radiating slots with different shapes etched on top broad wall to enhance bandwidth and radiation performance. With the special combination of the semiclosed SIW cavity and the slots, multiple resonances are generated in a close frequency range to broaden bandwidth. Furthermore, the proposed antenna is flush-mounted on a large metal plate to analyze the influence of platform on antenna performance. Measured results are in good agreement with simulation and show that the antenna bandwidth covers the frequency range 7.8~12.1 GHz for VSWR <; 2, with the fractional bandwidth of 43.2%. High gain of 7.8~11.8 dBi is obtained over the working band.