Closely Spaced Dual-band Quad-Element Compact MIMO Antenna with Polarization and Pattern Diversity

This paper describes a dual-band compact quad-element MIMO antenna design with pattern and polarization diversity. The compactness is achieved by considering an H shaped antenna element. The H-shaped antenna resonates at 3.525 GHz operating frequency. Two slots are incorporated at two wings of the H-shaped antenna to achieve dual-band operation. Thus, the slots provide a second resonant frequency at 4.82 GHz. The four elements are separated edge-to-edge by 0.046λ0 (where λ0 is the free-space wavelength at 3.525 GHz) and placed orthogonally to get diversity performance. The isolating networks are introduced between the elements, which provide enhanced isolation of 9.6 dB and 4 dB at lower and upper frequencies of operation respectively. The proposed antenna is fabricated and measured. The measured isolation at lower and upper bands is 16.5 dB and 16.4 dB respectively. The measured peak gains at the respective frequencies are 1.91 dB, -0.354 dB. The proposed antenna has a compact 2D profile having a total footprint of the antenna 0.42λ
₀
×0.42λ
₀
×0.0296λ
₀
.