A broadband low profile SIW cavity-backed antenna loaded with hexagonal and rectangular slots for ‘X’ band application

This article manifests a straight-forward design technique to obtain a broad bandwidth for a substrate integrated waveguide (SIW) cavity-backed slot antenna suitable for ‘X’ band applications. The combination of hexagonal and rectangular slots significantly expands the bandwidth, unlike conventional slots (circle, square, and triangle). They induce two closely spaced modes in the rectangular SIW cavity and improve the bandwidth of the resultant antenna. The proposed design is energized by a simple 50-Ω microstripline feed. The rectangular SIW cavity with dual slots enhances a bandwidth of 21.6%, covering ‘X’ band frequencies from 8.7 to 10.88 GHz. The proposed structure is very compact and occupies a square dimension of 29 \(\times 29\times 1.6\) $\times 29\times 1.6$ mm³ printed on an affordable FR4 substrate using printed circuit board technology. The proposed prototype is measured and validated with its respective simulated values, which reflect a fair agreement between them. The proposed design has an uncomplicated geometry, a simple feed technique, an enlarged bandwidth, and a low profile with a compact size that makes the proposed antenna an appropriate choice for defense tracking, weather monitoring, air traffic control, and RADAR applications.