# Dual-Band Multiple-Element MIMO Antenna System for Next-Generation Smartphones
###### Abstract  
This work presents a cost-effective multiple-element multiple-input multiple-output (MIMO) antenna system for next-generation smartphones. The proposed antenna system is developed on a 0.8 mm thin FR-4 substrate with a relative permittivity of 4.4, which consists of one main board and two sideboards. The dimensions of the main board and the two sideboards are 150 \(\times\) 75 mm\({}^{2}\) and 150 \(\times\) 6 mm\({}^{2}\), respectively. The radiating elements are printed on the sideboards to provide space for other radio frequency (RF) components to be embedded on the main board. The proposed antenna resonates at two distinct allotted 5G bands, i.e., 3.5 GHz and 5.4 GHz, with impedance bandwidths of 200 MHz and 700 MHz, respectively. The isolation between the antenna elements is noted to be \(>\)18 dB and \(>\)12 dB for the 3.5 GHz and 5.4 GHz frequency bands. In addition, the proposed MIMO antenna provides pattern and spatial diversity characteristics in both bands with good gain and efficiency. Furthermore, the MIMO parameters such as envelope correlation coefficient (ECC), mean effective gain (MEG), and channel capacity (CC) are calculated, and it is observed that the MIMO antenna offers good diversity performance for the bands of interest. A prototype is fabricated and measured to verify the numerical data. The simulated results were discovered to be in excellent agreement with the measured results. It is also observed that the proposed MIMO antenna system holds promising features, and can be utilized for future generations of smartphones. Keywords:dual-band; MIMO; 5G; pattern diversity; spatial diversity +
Footnote †: journal: _Applied_  
_Acticle_  
Dual-Band Multiple-Element MIMO Antenna System for Next-Generation Smartphones  
[PERSON], [PERSON], [PERSON], H.S.Mostafa, H.S.Rafique, U.K.  
to as the 5G mid-band, has the ability to extend coverage while reducing propagation losses. In order to accommodate higher data traffic for connectivity with higher data rates, a spectrum of 100 MHz is needed, which can easily be managed with the use of sub-6 GHz frequency bands. Additionally, to achieve high data rates and high CC, a minimum of six radiating elements is required. In the literature, several MIMO antenna systems have been proposed for the sub-6 GHz 5G spectrum. In [5], a six-element MIMO antenna was presented, which resonates in the frequency range of 3.4-3.6 GHz. The single element area was noted to be 24 mm\({}^{2}\), while the isolation among radiating elements was noted to be 11 dB. In [6], an open-ended slot radiation element-based MIMO antenna system was designed, which exhibits a 400 MHz impedance bandwidth ranging from 3.4 GHz to 3.8 GHz. They utilized 18 antenna elements for MIMO configuration and observed CC of 80 bps/Hz with 16 dB of isolation between antenna elements. In [7], an eight-element uni-planar MIMO antenna was presented, covering LTE band 42 over 3.4-3.6 GHz. A pair of orthogonally placed antenna elements are placed on each corner of the smartphone board. This arrangement leads to the achievement of high isolation between antenna elements, but the signal integrity is compromised because the antenna elements are placed very close to other electronic components. Along with LTE band 42 (3.4-3.6 GHz) and LTE band 43 (3.6-3.8 GHz), there are several other 5G bands, such as LTE band 46 (5.1-5.8 GHz), LTE band 41 (2.6-2.8 GHz), and n55 (4.4-4.8 GHz), which can be utilized to fulfill the basic requirements of 5G communication technology. In [8], a wideband MIMO antenna system was designed and presented for LTE band 41 and LTE band 42. The designed MIMO antenna exhibits a 1 GHz impedance bandwidth in the frequency range of 2.6-3.6 GHz. The MIMO configuration consists of eight elements, of which four elements are printed on the main board, while the four radiating elements are mounted on the side-edge frame of the smartphone. This kind of configuration leads to a complex design topology and also offers difficulties in the fabrication process.