A Millimeter Wave Elliptical Slot Circular Patch MIMO Antenna for Future 5G Mobile Communication Networks

Abstract

This paper proposes a 4-port MIMO (Multiple-Input Multiple-Output) antenna operating at 28 GHz in the millimeter wave band for future 5G communications. The first design in this work is a single-element circular shaped microstrip patch antenna with an elliptical slot and a defected ground structure which is intended for 28 GHz band. This antenna is compact with a size of 6 mm × 7 mm. A complete analysis of single patch element antenna is presented with the effect of slot and defected ground structure in Section 2. In Section 3, the second design, which is symmetric two-element MIMO slotted circular patch antennas, is analyzed with the dimension L × W as 7 mm × 6 mm. In Section 4, the final fabricated design is presented, which is a 4-port MIMO antenna operating at the resonance frequency of 28 GHz along with the improved isolation between the elements due to appropriate spacing. The proposed 4 port MIMO antenna is designed on a Rogers Duroid 5880 substrate having a relative dielectric permittivity of 2.2 and thickness of 0.8 mm. The overall dimension of this designed MIMO antenna is 20×20×0.8 mm3. Simulated results for the S-parameters and radiation pattern are presented for all purposed designs using CST software. Measured results are also presented for the return loss using Rhode & Schwarz ZVA 40 vector network analyzer. Simulated and measured results show a good agreement. The simulation results demonstrate that the return loss at individual port is less than −10 dB in the frequency range of 26.867–28.975 GHz, and it provides a bandwidth of 2.1 GHz. The antenna has a high gain of 9.24 dB with unidirectional radiation pattern, and each element has a mutual coupling less than −20 dB.