In this paper, a compact planar dual-band multiple-input and multiple-output (MIMO) antenna with high isolation is presented to satisfy the increasing requirements of wireless communication. The proposed antenna array consists of two identical radiating elements which are fed through micro-strip lines. A rectangular micro-strip stub with defected ground plane is employed to achieve a high isolation which is less than −15 dB between the two antenna elements. The size of the entire MIMO antenna is 32 × 32 × 1.59 mm3, which is printed on an FR4 substrate. The proposed MIMO antenna is optimized to operate in 2.36–2.59 GHz and 3.17–3.77 GHz bands, which can cover the fifth-generation (5G) n7 (2.5–2.57 GHz) and the fourth-generation (4G) Long Term Evolution (LTE) band 42 (3.4–3.6 GHz). The proposed MIMO antenna is feasible for the 5G and 4G applications.

A two-port multiple-input and multiple-output (MIMO) antenna with dual-band characteristics operating at the fifth-generation (5G) new radio (NR) sub-6 GHz n7/n38/n41/n79 bands is proposed. The proposed MIMO antenna is composed of two symmetric antenna elements and a defected ground plane. The antenna element consists of an incomplete circular patch with two L-shaped branches. By applying the defected ground structure and the slotted stub, the current distribution on the ground plane is changed to reduce the mutual coupling between the antenna elements. The measured −10 dB reflection coefficients cover 2.34–2.71 GHz and 3.72–5.10 GHz, while the measured isolation is larger than 20 dB at the whole operating frequency band. The paper has investigated different performance parameters in terms of the envelope correction coefficient (ECC), diversity gain (DG), radiation patterns, antenna gain, and efficiency. The proposed MIMO antenna is suitable for 5G applications.

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A compact multi-input multi-output (MIMO) antenna system with dual-band characteristics is presented in this paper. The radiating element consists of an E-shaped strip and a modified arrow-shaped strip. The utilization of the modified arrow-shaped strip can generate dual-band operation while the isolation is enhanced by neutral line structure. The measured À10 dB reflection coefficient can cover 2.28-2.7 GHz and 4.96-6.1 GHz frequency bands. The mutual coupling is less than À15 dB over the lower and higher frequency bands. The envelope correlation coefficient is less than 0.06. The proposed MIMO antenna is a good candidate for 5G/WLAN/Bluetooth applications.

A wideband multiple-input multiple-output (MIMO) antenna with high isolation for fifth-generation (5G) new-radio (NR) smartphone employment operating at a range from 3.3–5 GHz is presented in the paper. The wideband antenna is comprised of eight identical radiation units and applies defected ground structure (DGS) to offer higher isolation between antenna units. Each of the antenna elements is formed of a C-shaped microstrip line, two triangle-shaped strips and a rectangular strip. The measurement results present that the transmission coefficients of the presented antenna are smaller than −18 dB in the required wideband, and the envelope correlation coefficient (ECC) values are better than 0.005. The realized gain and efficiency of the designed antenna are about 3.5 dBi and higher than 75%, respectively. The volume of this total antenna is 150 × 75 × 7 mm3, and the measurement of each antenna unit is merely 6.8 mm × 7 mm × 0.8 mm (0.077 λ×0.08 λ×0.009 λ, λ is the wavelength of 3.4 GHz). The presented MIMO antenna is suitable for 5G new-radio (NR) smartphone applications.