This study presents the design and analysis of a compact 28 GHz MIMO antenna for 5G wireless networks, incorporating simulations, measurements, and machine learning (ML) techniques to optimize its performance. With dimensions of 3.19 λ₀ × 3.19 λ₀, the antenna offers a bandwidth of 5.1 GHz, a peak gain of 9.43 dBi, high isolation of 31.37 dB, and an efficiency of 99.6%. Simulations conducted in CST Studio were validated through prototype measurements, showing strong agreement between the measured and simulated results. To further validate the design, an equivalent RLC circuit model was developed and analyzed using ADS, with the reflection coefficient results closely matching those from CST. Additionally, supervised ML techniques were employed to predict the antenna’s gain, evaluating nine models using metrics such as R-squared, variance score, mean absolute error, and root mean squared error. Among the models, Random Forest Regression achieved the highest accuracy, delivering approximately 99% reliability in gain prediction. This integration of machine learning with antenna design underscores its potential to optimize performance and enhance design efficiency. With its compact size, high isolation, and exceptional efficiency, the proposed antenna is a promising candidate for 28 GHz 5G applications, offering innovative solutions for next-generation wireless communication.

In this paper, a new metamaterial absorber (MMA) has been presented that shows dual-band absorption at 1.8 GHz and 3.5 GHz. The MMA cell has been designed on an FR4 substrate with the electrical dimension of 0.14λ₀ × 0.14λ₀ × 0.01λ₀, calculating wavelength, λ₀ at 1.8 GHz. Maximum absorption of 98.7% and 99.7% are attained by a unique design of a resonating patch consisting of two modified circular rings that are finalized through numerical Simulation in CST microwave studio. The MMA exhibits high angular stability up to 60° for incident angle as well as polarization angle variations. The analogous equivalent circuit is modeled in advanced design system (ADS) software, providing the same reflection, transmission, and absorption characteristics of 3D Simulation in CST. The absorption mechanism is investigated through current and electromagnetic field analysis. The MMA exhibits negative permittivity within 1 GHz—1.8 GHz and 2.08 GHz – 3.49 GHz and negative permeability with other frequency ranges. The prototype of a 3 × 6 array of the MMA cell is developed, and measurement is accomplished. The measured result exhibits well match with the simulated result. Moreover, The MMA displays good shielding effectiveness of 40.12 dB and 36.81 dB at 1.8 GHz and 3.5 GHz, respectively. The quality factors of the MMA are 30 and 22.3, with half power bandwidth of 60 MHz and 157 MHz. This new and unique MMA can be incorporated with various electronic devices for microwave shielding from GSM 1.8 GHz and sub-6, 5G 3.5 GHz signals.

In this paper, a miniaturized branch-line coupler is proposed. The topology of the circuit is designed using novel design of T-model approach with open stubs with high-low impedances, which provides necessary bandwidth for WLAN band at 2.45 GHz. The miniaturized branch-line coupler is designed and fabricated with a low-cost FR4 substrate as a platform in producing significantly reduction by more than 64.21% compared to the conventional coupler on inexpensive board. Furthermore, the coupler can equally divide the input signal with 90 • phase of difference while maintaining the initial power from the source.

A multipurpose antenna system that can handle a broad area of frequencies is crucial in the effort to build up widespread 5G Internet-of-Things (IoT) networks. For fifth-generation Internet-of-things applications, this research introduces a new multi-band antenna that can operate in the sub-6 GHz band (2–7 GHz), Ku-band (13–17.5 GHz), and millimeter wave band (25–39 GHz). The antenna achieves a remarkable three-band operational bandwidth through cleverly integrated slots and parasitic components. Maximum realized gain of 4.3 dBi in the sub-6 GHz band, 5.5 dBi in the Ku-band, and 9.9 dBi in the millimeter wave (mm-wave) band for 3D MIMO setup is ensured. In addition, the machine learning prediction is used to verify the single element realized gain, and the results demonstrate that it performs admirably with an accuracy of more than 89% using the random forest regression model throughout the entire frequency spectrum. A 6-port, one-of-a-kind MIMO design with strong diversity performance is built from the single-element configuration. This 6-port MIMO system uses a new codesign technique to achieve 360-degree coverage in the elevation and azimuth planes, exceptional isolation (21 dB at sub-6 GHz band, 25 dB at the Ku-band, and 30 dB at mm-wave band), and pattern diversity. This MIMO antenna module is a shining example of the future, with the potential to completely alter the state of affairs in terms of 5G IoT connectivity in settings such as smart homes, offices, cities, vehicle-to-everything communications, and broadcast satellite service (BSS).

This paper introduces an innovative 4×4 dual-band Butler matrix (BM) characterized by compactness and an enhanced frequency ratio (K). The design employs meandered lines and an interdigital capacitor unit cell based composite right/left-handed transmission-line (CRLH-TL) metamaterial (MTM) structure. The BM integrates compact dual-band 3 dB branch-line couplers (BLC), a 0 dB crossover, and a dual-band 45° phase shifter on a single Rogers RT5880 substrate (with ε _r = 2.2 and h = 0.787 mm). Simulations and measurements results demonstrates reflection and isolation coefficients exceeding -20 dB at all ports, with a obtained insertion loss of -6±3 dB over the 0.7 GHz and 3.5 GHz frequency bands. The achieved phase differences of ±45°, ±135°, ±135°, and ±45° indicate a maximum average phase tolerance of ±4.5°. Importantly, the BM’s overall dimensions are 140 mm × 192 mm, resulting in a 78% size reduction compared to traditional BM designs. The proposed configuration is designed and simulated using CST Microwave Studio, with the agreement between simulated and measured parameters highlighting design reliability and effectiveness. Additionally, a performance evaluation comparing the proposed BM with existing circuits reveals its suitability for sub-6 GHz 5G dual-band antenna array beamforming networks (BFN) due to its compact size and improved band ratio.