Abstract
A broadband compact-sized planar four-port multiple-input–multiple-output (MIMO) antenna with polarization diversity is presented. The proposed dual circularly polarized (CP) MIMO antenna consists of four G-shaped monopole elements, two of which are left-hand CP and the other two are right-hand CP. A vertical line strip in the G-shaped radiating element acts in balancing the vertical and horizontal electric field components to obtain 90° phase difference between them for circular polarization. Also, an I-shaped strip is incorporated between the ground planes of the G-shaped antenna elements to obtain equal voltage level in the proposed MIMO configuration. The dual circular polarization mechanism of the proposed MIMO/diversity antenna is analysed from the vector current distributions. The impedance bandwidth (S11 ≤ –10 dB) of the MIMO antenna is 105.9% (4–13 GHz) and the 3 dB axial ratio bandwidth (ARBW) is 67.7% (4.2–8.5 GHz), which is suitable for C-band applications. The overall size of the MIMO antenna is 70 × 68 × 1.6 mm3, and the minimum isolation between the resonating elements is 18 dB. The envelope correlation coefficient is less than 0.25, and the peak gain within the resonating band is 6.4 dBi.
Highlights
The introduction of spatial diversity in wireless communication systems has improved their performance significantly [1,2]
In multi-antenna systems, the coupling among radiating elements reduces the performance of the system and, various techniques have been explored to increase inter-element isolation [4,5]
This paper presents a compact dual-circularly polarized (CP) MIMO antenna with broad axial ratio bandwidth (ARBW)
Summary
The introduction of spatial diversity in wireless communication systems has improved their performance significantly [1,2]. As compared to single antenna systems, the MIMO arrangement provides high spectral efficiency, high capacity, and reliable communication between the transmitting and receiving terminals [3]. In multi-antenna systems, the coupling among radiating elements reduces the performance of the system and, various techniques have been explored to increase inter-element isolation [4,5]. The orthogonal placement of the antenna elements in a MIMO configuration was frequently used as one of the efficient decoupling methods but, at the same time, it increases the design complexity [6]. Other decoupling methods used neutralization lines, electromagnetic band-gap (EBG), frequency-selective surface (FSS), and parasitic elements [5]
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