Quad-band two-port MIMO antenna serving for sub-7 GHz frequency with integrated circularly polarized bands

Abstract

A novel-shaped miniaturized quad-band two-port multiple input multiple output (MIMO) antenna with integrated circular polarization is proposed. The proposed antenna resonates at four bands i.e.900 MHz, 1800 MHz, 3.5 GHz and 5.5 GHz. Moreover, the antenna offers circular polarization at three bands centred at 900 MHz, 1800 MHz, and 6 GHz. The C-shaped iterated antenna is integrated with a circular slot in the ground plane, that contributes to wide impedance bandwidth at respective frequencies. The measured results confirm −10 dB impedance bandwidth of 400 MHz (0.7–1.1 GHz), 430 MHz (1.57–2.0 GHz), 2.74 GHz (2.19–4.90 GHz) and 1.4 GHz (5.30–6.70 GHz) with 3 dB axial ratio bandwidth of 400 MHz (0.7–1.1 GHz),400 MHz (1.6–2.0 GHz) and 1.3 GHz (5.40–6.70 GHz), respectively. The exhibited antenna shows the independent tuning of each resonant band, which is another significant merit of the proposed antenna. Furthermore, good isolation of a maximum value of –22 dB is maintained within all four bands. The two-port MIMO antenna is designed on an FR4 epoxy substrate of size 42 × 40 mm2(0.1008λ0 × 0.096λ0).