Wideband planar substrate integrated waveguide cavity-backed amended dumbbell-shaped slot antenna

In this article, a novel design of wideband planar substrate integrated waveguide (SIW) cavity-backed antenna (CBA) consisting of amended dumbbell-shaped slot and two cylindrical metal vias is developed. The simple dumbbell slot perturbs the current distribution of the both TE110 and TE210 cavity modes and generates the three independent modes (half-TE110, even-TE210, and odd-TE210) at distinct frequencies. When the two metallic vias are loaded at the middle portion of the SIW cavity and due to simultaneous excitation, two hybrid modes come close to each other. These hybrid modes serve to widen the fractional bandwidth upto 17.36%. The bandwidth is further extended by modifying the simple dumbbell slot. A specimen is fabricated to validate the amended dumbbell-shaped slot experimentally. The proposed antenna offers two resonances and exhibits a fractional bandwidth of 22.4% (2.25 GHz). The antenna renders measured peak gains of 6.45 dBi and 6.2 dBi at 9.2 GHz and 10.6 GHz, respectively. Furthermore, the proposed design shows the front-to-back-ratio 14 dB and cross-polar levels -28 dB and -37 dB maximum at both the measured frequencies. Those amicable characteristics, e.g., low-profile, low cross-polarization levels, unidirectional radiation pattern, and wide impedance bandwidth, make the proposed antenna appropriate for X-band applications.