Self-Isolated MIMO Antenna Using SIW Cavity Antenna for Dual-Band (28, 38 GHz) Applications

This paper introduces a substrate integrated waveguide (SIW) antenna for dual-band applications. The antenna comprises a SIW cavity and a rectangular ring slot on the top metal layer for the radiation. Two different modes, i.e., <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TM₁₀₀</tex> patch mode and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">half-TE₃₁₀</tex> cavity mode, are excited in the cavity so that the antenna operates in 28/38 GHz band. Also, the radiation mechanism of the proposed SIW antenna with its electric and magnetic field distributions is provided. The single antenna element achieves a fractional bandwidth of 6.65% (26.91-28.76 GHz) and 1.45% (37.71-38.25 GHz) at the two resonant frequencies. Also, the peak gain of 6.57 dBi and 4.56 dBi is achieved in their respective bands. Further, utilizing the SIW cavity property of self-isolation, a four-element MIMO antenna is presented. The MIMO antenna exhibits the fractional bandwidth of 6.69% and 1.23% with minimum port-to-port isolation of 28.48 dB and 22.45 dB within the operating bands.