This paper presents the design and realization of a simple and low-profile, four-port multiple-input-multiple-output (MIMO) antenna operating in a mm-wave band supporting 5G communication technologies. As part of the design methodology, the initial stage involved the development of a conventional monopole patch antenna optimized for operation at 26 GHz, which was matched to a 50 Ω stepped feed line. Afterward, a square-shaped defected ground structure (DGS) with semi-circle slots on the edges was placed on the ground to improve the isolation, and the circular and rectangular slots were incorporated as DGSs to optimize the antenna impedance bandwidth. Etching semi-circular-shaped slots on the ground plane achieved more than 34.2 dB isolation in the 26 GHz operating band. In addition, an arrangement of four symmetrical radiating elements was positioned orthogonally to minimize the antenna’s physical size and improve the isolation. The proposed MIMO antenna’s overall dimension was 25 × 25 mm2, which was printed on a Rogers 5880 substrate at a width of 0.787 mm and εr = 2.2. The proposed antenna covered the 5G mm-wave band with a 10 dB bandwidth ranging from 25.28–28.02 GHz, whereas the maximum gain attained for the proposed structure was 8.72 dBi. Additionally, the implementation of these slots effectively mitigated mutual coupling, resulting in reduced envelope correlation coefficient (ECC) values. Furthermore, other MIMO performance metrics, including channel capacity loss (CCL), mean effective gain (MEG), and diversity gain (DG), were analyzed for the proposed structure. The obtained results indicate its suitability for various usage areas, such as smart devices, mobile phones, and sensors in 5G applications.

The small volume of microstrip antennas has low production costs and easy production, which has accelerated the work in this area. The disadvantages are narrow bandwidth and low gain. In wireless communication, antennas with low return loss and high bandwidth are required. The bandwidth and power gain of the microstrip patch antennas should be increased optimally. This article presents the design of the broadband microstrip patch antenna operating in the ISM 2.4 GHz band (2400-2485 MHz). The study includes three-dimensional antenna model, simulation phase and fabrication / measurement phase. For the low cost of the antenna, FR-4 with the relative dielectric constant 4.3 and the loss tangent tan 0.02 is preferred as the substrate material. Dielectric material thickness is determined as 1.6 mm. The length of the feed line and the dimensions of the rectangular patch were found by mathematical calculations with the transmission line model. There are slots on the antenna, which is a very simple method in order to improve the bandwidth, gain and directivity parameters of the antenna. In the article, four different designs are presented, the results are compared and the proposed antenna has 979 MHz bandwidth and 2.68 dBi directivity gain at -10 dB at the resonance frequency of 2.316 GHz. The changes made in the antenna design have improved the results such as gain and bandwidth compared to the conventional microstrip patch antenna. The proposed antenna is suitable for use in mobile communication.

This paper presents the design and realization of a simple and low-profile, 4-port Multiple-Input-Multiple-Output (MIMO) antenna operating in the mm-wave band supporting 5G communication technologies. As part of the design methodology, the initial stage involved the development of a conventional monopole patch antenna optimized for operation at 26 GHz, which is matched to 50 Ω stepped feed line. Afterward, a square-shaped Defected Ground Structure (DGS) with semi-circles slots on the edges is placed on the ground to improve the isolation and the circular and rectangular slots are incorporated as DGS to optimize the antenna impedance bandwidth. Etching semi-circular shaped slots on the ground plane achieved more then 34.2 dB isolation in the 26 GHz operating band. In addition, an arrangement of four symmetrical radiating elements is positioned orthogonally to minimize the antenna’s physical size and to improve the isolation. The proposed MIMO antenna overall dimension is 25 × 25 mm2, which is printed on Rogers 5880 substrate with a width of 0.787 mm and εr = 2.2. The proposed antenna covers the 5G mm-wave band with a 10 dB bandwidth ranging from 25.28 - 28.02 GHz, whereas the maximum gain attained for the purposed structure is 8.72 dBi. Moreover, the proposed design, simulated and measured with advantages such as high isolation, low ECC, simple and compact design, is a good candidate for usage areas such as smart devices, mobile phones, and sensors in 5G applications.