This article presents a simple planar millimeter-wave (mm-wave) multiple input multiple output (MIMO) antenna with four closely spaced radiating elements. The antenna is intended to enhance the bandwidth for 5G new radio (NR) applications and also cover the industrial Ka-band (26.5-40 GHz), Q-band (30-50 GHz), and U-band (40-60 GHz) frequency ranges. The antenna is designed using Rogers RT/duroid 5880 substrate with a size of mm³. The proposed antenna consists of four identical radiating elements with two of them positioned in a linear configuration facing each other, while the other two elements are placed opposite to the first two, which improves isolation between the elements. Across the entire operating frequency range (26-60 GHz), the antenna demonstrated excellent performance, including 34 GHz wide bandwidth, high isolation of >25 dB, nearly omnidirectional radiation patterns, high gain of 11.1 dB with a high radiation efficiency of 94%, low envelope correlation coefficient (ECC) of 0.0068, and high diversity gain (DG) of 9.967 dB. The simulated findings exhibit a strong positive correlation with the experimental results. The proposed MIMO antenna design is a promising solution for 5G NR applications.

As the same device may be used for various types of applications, antennas must have the capacity to perform multiple functions. Reconfiguring the polarization, operational frequency, and radiation pattern can create an outcome of multi-functionality. A hybrid, frequency- and pattern-reconfigurable antenna with two V-shaped extrudes in a patch is proposed. To increase the bandwidth of the proposed antenna, the defected ground structure (DGS) phenomenon is presented, which is significant in the bandwidth of 3200 MHz from 2.7 GHz to 5.9 GHz, providing a gain of 3.5 dB. For this design, an FR-4 material was chosen as the substrate, and CST software was used for simulation. Using two p-i-n diodes, the projected antenna illustrates switching for multi-frequency bands such as 1.5, 2.6, 3.2, 5.1, and 8.1 GHz, with a constant radiation pattern and a main lobe direction of 155 degrees. It has C-band, WLAN, cognitive radio (CR), and Bluetooth applications. The proposed antenna displays radiation pattern switching at 3.5 GHz, showing variation between 7°, 158°, 173°, and 175°, and at 4 GHz, it demonstrates switching between 11°, 15°, 165°, and 344°, which defines the hybrid reconfiguration.

This article is based on dual fractal techniques to design the Koch–Sierpinski Fractal Microstrip (KSFM) antenna for wireless applications. The concept of the Koch fractal is applied on the outer periphery of the square-shaped patch and Sierpinski gasket concept on the inner segment of the square-shaped patch to reduce the effect of surface currents. The antenna design involves two degrees of iteration using dual fractal techniques. The antenna is simulated using HFSS software and fabricated. The measurements of antenna parameters are done using a vector network analyser (VNA). The proposed antenna covers multiband resonant frequencies of 5.699 GHz, 10.108 GHz, 11.100 GHz, 15.812 GHz and 17.621 GHz for C-band (4–8 GHz), X-band (8–12 GHz) and Ku-band (12–18 GHz) applications. The antenna achieved better bandwidth at high range of frequencies. Three different substrates were chosen to compare the results of the proposed antenna (Fr4, Rogers RO 4003 and Rogers Ultralam) with the Fr4 substrate achieving the best results. The simulation agreed well with those obtained experimentally.

In this research, a circularly polarized antenna employing fractal slot geometry is proposed for UHF-RFID handset reader application. The proposed antenna consists of vicsekcross-shaped slot etched at diagonal axis to achieve circular polarization with a coaxial feed placed 45∘ with respect to the slot. The evolution of Vicsekcross shaped fractal slot is developed in different iteration stages for achieving wide impedance bandwidth covering U.S. UHF-RFID band with good axial ratio bandwidth performance. The single slotted reader antenna was investigated first followed by multi-slot antenna for size miniaturization, impedance bandwidth and axial ratio bandwidth performance. The impedance bandwidth and axial ratio bandwidth of the designed antenna were observed to be 25 MHz (903-927 MHz) and 7 MHz (911-917 MHz), respectively. Additionally, the designed antenna exhibited LHCP with a maximum measured gain of 2.9 dBic. The size of the final Vicsekcross-shaped four slot CP reader antenna is compact with dimensions of 57 x 57 x 1.6 mm.

The design and analysis of frequency selective surface (FSS) on the modified ultra-wideband structure (UWB) is presented in this paper. The UWB structure has ci The design and analysis of frequency selective surface (FSS) on the modified ultra-wideband structure (UWB) is presented in this paper. The UWB structure has ci

A notable progress in antenna design, especially concerning multiple-input multiple-output (MIMO) antennas, is being driven by the emergence of 5G technology. One of the preliminary steps in constructing a multiple-input and multiple-output antenna involves choosing a suitable substrate material and thickness. The careful selection of dielectric substrate material and its thickness significantly influences the key characteristics such as physical dimensions, bandwidth, and radiation efficiency. This study presents the design and evaluation of a 4 Å~ 4 circularly polarized multiple-input and multiple-output antenna tailored for 5G applications, with focus on evaluating four dielectric substrates, Flame Retardant 4, RT/Duroid5880, RT/Duroid6002, and Rogers RO3003. All antennas were modeled and investigated through full-wave simulations using ANSYS High-Frequency Structure Simulator, with a uniform substrate thickness of 0.8 mm. Based on simulated results, RT/Duroid 6002 was selected for fabrication. The fabricated antenna operates in the range of 15 GHz–45 GHz, and achieves a wide measured bandwidth of approximately 13.5 GHz in this operating range. Measurements were conducted using a vector network analyzer and an anechoic chamber. The envelope correlation coefficient was found to be 0.001, indicating excellent diversity performance along with diversity gain and total active reflection coefficient. The study provides valuable insights into the direct effects of dielectric substrate properties on an antenna’s operation and guides substrate selection for the development of compact, wideband antenna arrays suitable for 5G mm-wave systems. Cite this article as: A. Baliyan, M. G. Siddiqui, K. S. Kharb and A. Singh, “Quad-port circularly polarized ring slot multiple-input multiple-output antenna for 5G UWB wireless communication systems,” Electrica, 26, 0258, 2026. doi: 10.5152/electrica.2026.25258.