Collocated Microstrip Slot MIMO Antennas for Cellular Bands Along With 5G Phased Array Antenna for User Equipments (UEs)

In this paper, three different microstrip slot radiators are proposed on single user equipment (UE) size ground plane providing flexibility for the user to utilize many useful bands such as some lower cellular bands, Sub-6 GHz band, and <italic>mm</italic>-wave 5G band. First, a 2-port multiple-input-multiple-output (MIMO) antenna (<italic>Type-I</italic>) utilizing polarization diversity is designed for useful cellular bands from 1.6–2.2 GHz and 2.5-2.7 GHz (<inline-formula> <tex-math notation="LaTeX">$\vert \text{S}_{11}\vert < -6$ </tex-math></inline-formula>dB, <inline-formula> <tex-math notation="LaTeX">$\vert \text{S}_{21}\vert < -20$ </tex-math></inline-formula>dB) with a realized gain of around 4 dBi. Second, two 2-port MIMO antennas (<italic>Type-II</italic>) are designed for sub-6 GHz 5G band from 3.3 - 5 GHz (<inline-formula> <tex-math notation="LaTeX">$\vert \text{S}_{11}\vert < -10$ </tex-math></inline-formula>dB, <inline-formula> <tex-math notation="LaTeX">$\vert \text{S}_{21}\vert < -15$ </tex-math></inline-formula>dB) with a realized gain around 7 dBi. A new connected meander ground slot is introduced here as a decoupling structure. Third, two circularly polarized <inline-formula> <tex-math notation="LaTeX">$1\times 8$ </tex-math></inline-formula> linear arrays (<italic>Type-III</italic>) is designed for the 5G band from 27 - 29GHz (<inline-formula> <tex-math notation="LaTeX">$\vert \text{S}_{11}\vert < -10$ </tex-math></inline-formula>dB) with an adjacent port isolation greater than 20 dB and a realized gain around 12dBiC. The proposed phased array is also implemented using the SiGe RFIC (ADMV4821) based 5G analog beamformer. A beam steering of ±30° is achieved along the array axis. The performances of the prototype are also characterized in the presence of other major metallic components, hand, and head phantom. The simulated and experimental results make the different MIMO antennas and 5G phased arrays enabled prototype as a suitable candidate for future UEs.