An Integrated DRA-Based Large Frequency Ratio Antenna System Consisting of a MM-Wave Array and a MIMO Antenna for 5G Applications

This paper presents a large frequency ratio antenna that covers the widely separated 5G bands. The proposed antenna consists of a 2-element rectangular DRA (rDRA)-based MIMO antenna for the sub-6 GHz band, with an embedded
$1\times 4$
cylindrical DRA (cDRA) array covering the mmW band. The rDRAs are fabricated through a cost and time-efficient 3D printing process, whereas small dimensions of cDRAs are precisely machined through a CNC. The proposed antenna has a measured impedance bandwidth of 31.63% at 4.9 GHz and 21.5% at 28 GHz. The antenna has a peak gain of 6.6 dBi at the sub-6 GHz and 12 dBi at the mmW bands. Moreover, the proposed antenna has an Envelope Correlation Coefficient (ECC) of less than 0.01, whereas the simulated beam steering performance of the antenna exhibits good performance for the sector of ±50°.