Multiband SIW Cavity-Backed Antenna Using Inverted U-Shaped Slot and Metallic Strip for WIMAX/WLAN Applications

In this research paper, a simple design for a cavity-backed antenna with a small profile Substrate Integrated Waveguide (SIW) containing a thin U-shaped slot with a conductive strip is developed for generating three resonant frequencies suitable for WIMAX/WLAN applications. A single low-cost dielectric substrate of Flame Retardant-4 (FR-4) Epoxy is used to produce the whole antenna, including the backed cavity and inset microstrip feed line. Due to the loading impact of the U-shaped slot, a hybrid mode is induced by perturbing the cavity modes $\mathbf{TE_{210}}$. The multiband antenna has been simulated using the High-Frequency Structure Simulator (HFSS) software, which exhibits a low reflection coefficient of less than -27.2dB, -44.4dB, and -26.2dB at the operating frequencies of 3.68 GHz, 4.93 GHz, and 5.71 GHz, respectively. Moreover, the design provides a high power handling capacity with low mismatch loss, as verified by the input impedance $\mathbf{Z}$ and the Voltage Standing Wave Ratio (VSWR) values. Besides, the suggested antenna offers a reasonable gain and a broadside radiation pattern.