Multiband substrate integrated waveguide antenna loaded with slots using artificial neural network

Abstract

A miniaturized cavity-backed antenna loaded with slots is designed using substrate integrated waveguide (SIW) technique for ISM/WiMAX/C-band/RFID applications. This antenna has been developed by embedding slots onto a hexagonal cavity for quad band radiation. The proposed antenna possesses hexagonal cavity, inverted U-shaped slot and innermost inverted U-shaped slot, which are governed by an inset microstrip feedline. The hexagonal SIW cavity-backed antenna offers cavity modes TM 110 $$ {\mathrm{TM}}_{110} $$ at 4.16 GHz and TM 210 $$ {\mathrm{TM}}_{210} $$ at 5.8 GHz. Two inverted U-shaped slots are introduced on the top metallic surface of the cavity to drive the lower resonant modes for acquiring antenna miniaturization. These lower resonance frequencies are formed by hybrid mode (i.e. TM 110 + TM 210 $$ {\mathrm{TM}}_{110}+{\mathrm{TM}}_{210} $$ ) at 2.4 GHz and coupling of hybrid mode (i.e. TM110 + hybrid mode + TM210) at 3.33 GHz. The ANN optimization method has been performed to enhance the performance of the antenna using MATLAB. The designed antenna has a compact size of 25 × 25 × 1.6 mm3, which is fabricated on a low cost FR-4 substrate having ε r = 4.4 $$ {\varepsilon}_{\mathrm{r}}=4.4 $$ and tan δ = 0.002 $$ \tan \delta =0.002 $$ . To validate the simulated equivalence, the fabricated antenna has been measured. It yields a fractional bandwidth of 5.04% (2.31–2.43 GHz) in the hybrid mode at 2.38 GHz, 6% (3.22–3.42 GHz) in the coupling of hybrid mode at 3.33 GHz, 19.19% (3.97–4.78 GHz) in the cavity mode TM 110 $$ {\mathrm{TM}}_{110} $$ at 4.22 GHz and 7.2% (5.69–6.11 GHz) in the cavity mode TM 210 $$ {\mathrm{TM}}_{210} $$ at 5.8 GHz with stable radiation pattern.