The design of low-profile Multiple-Input-Multiple-Output (MIMO) antennas for various 5G applications is a topic of huge interest in academia, research, and telecommunication sector. In this aspect, a compact and low-profile 5G MIMO antenna has been designed and analyzed for various 5G applications, specifically for the 24 GHz bands (24.25–24.45 GHz and 25.05–25.25 GHz) and local multipoint distribution system band (27.5–28.35 GHz) of the 5G spectrum. The proposed antenna structure is 20 × 20 × 1 mm3 in dimension. Two spade-shaped radiators composed of Copper (annealed) material are placed orthogonally to improve isolation and maintain signal diversity. Rogers RT 5880 is used as the material for substrate. The antenna exhibits a wide bandwidth of 21.5–28.5 GHz. The mutual isolation |S21| has been maintained ≤29 dB due to the insertion of a T-shaped parasitic strip in between the radiating elements. Novelty in design and superiority in performance has been observed when compared with related antenna categories.

This article introduces an innovative approach to antenna array design, focusing on synthesizing the optimal radiation pattern for fifth-generation (5G) communication. The authors have designed a reliable linear and elliptical antenna array (EEA) of dipole elements by employing sailfish optimization (SFO). 5G technology promises transformative improvements in wireless communication with high data rates, expanded capacity, minimal latency, and exceptional service quality. The crux of 5G lies in the precision of antenna array design, aiming for an emission pattern with minimal side lobe levels (SLLs) and a narrow half-power beam width (HPBW). A narrower HPBW is essential for efficient long-range communication, whereas reducing the SLLs enhances signal clarity. The SFO optimizes the current excitation of each antenna element for reducing the mutual coupling effects and lowering the SLL and HPBW values in linear and EEAs. This paper uses the exact excitation to each element to show the linear antenna arrays (LAA) (10-, 16-element) design examples and EAA (8-, 12-, 20-element) structures. The LAA and EAA design examples obtained with the SFO algorithm establish the advancement in SLL suppression over the uniform antenna array and the methods proclaimed in the recent article.

This paper describes a multiple-input multiple-output (MIMO) antenna for low millimeter (mm)-wave applications based on dielectric resonators. This is the first time that a filtering response is used in conjunction with an MIMO antenna operating at a low mm-wave frequency. The antenna is simulated using an asymmetrical U-shaped aperture and a microstrip line feed. The suggested filtenna has two distinguishing characteristics: (i) the diversity parameters of the proposed MIMO are increased by including pattern and spatial diversity, and (ii) the proposed feed mechanism of a dielectric resonator provides the filtering response. Between the two ports, a metallic plate tilts the radiation pattern by 45°. The anti-parallel locations of the ports increase the isolation value by >30 dB. To validate the performance of the suggested antenna, the proposed filtenna was built and confirmed. The proposed antenna operates between the frequencies 27.9 and 28.5 GHz. Within the operating frequency range, the observed gain is ~4.5 dBi. On the contrary, the gain suppression level beyond the operational frequency range is ~15 dB. The stable radiation properties and high diversity parameter values of the suggested filtenna make it an effective solution for 5G Internet of Things sensing applications.

In this paper, a dual-band 8 × 8 multi-input multi-output (MIMO) array antenna operating in 3.5 GHz band (3400–3600 MHz) and 5.5 GHz band (5150–5925 MHz) for 5G mobile handset is presented. The proposed hybrid antenna includes a comb-shaped monopole and an L-shaped open slot antenna which are symmetrically located on the inner surface of the side-edge frame of smartphone. Pattern diversity is achieved that can mitigate envelope correlation coefficients (ECCs) and improve the MIMO system performances. The prototype of proposed dual-band eight-element MIMO antenna is fabricated and experimentally measured. The results show that isolation <−10 and <−15 dB, respectively in the lower band and high band without any additional decoupling element are achieved and the desired bands are satisfied under the condition of −6 dB impedance matching. Moreover, the essential parameters for evaluation of the MIMO system performance such as the ECC, mean effective gain (MEG), and ergodic channel capacity are calculated. Furthermore, the influence of user's hand on the radiation characteristics of proposed MIMO antenna are also investigated and discussed. Based on the result, the proposed MIMO antenna is a good candidate for use in future 5G applications.

A new wideband multiple-input/multiple-output (MIMO) antenna system able to operate in a frequency band ranging between 3.3 and 7.1 GHz is proposed for fifth-generation (5G) new radio applications for future smartphones. The design structure contains four pairs of compact microstrip-fed slot antennas, located at the corners of an FR-4 printed circuit board. Each pair of antennas consists of a radiator with two concentric annular slots, fed by two L-shaped microstrip-feeding lines and provides polarization and radiation pattern diversity function due to the orthogonal placement of their feed-line. In order to reduce the mutual coupling characteristic, we have inserted a rectangular slot under each microstrip feed-line. Besides, we have coupled and linked the two rings by a small gap to combine and move the resonant modes so as to achieve wideband coverage. The measured and simulated results show that the proposed design achieves the desired performance, such as isolation >12 dB, a total efficiency >48%, and an envelope correlation coefficient <0.07. In addition, the radiation pattern, the total efficiency, the realized gain, and the channel capacity are also studied. According to the reached results, the proposed MIMO antenna may be a suitable application-oriented design for 5G mobile communication.

A planar rectangular slot antenna with dual-band operation and realized higher peak gain is proposed, designed, and fabricated for sub-6 GHz 5G applications. The antenna possesses a rectangular radiating slot with the inverted stub on its upper edge excited simultaneously by a micro-strip feed line having a double folded T-shaped structure. The fabricated design is of compact size with the radiating portion of 0.3 λ0 × 0.17 λ0 (λ0 represents free-space wavelength) and profile of 0.009 λ0. The measured results show the operating frequency bands of 3.29–3.63 GHz and 4.3–5.2 GHz, with a peak gain of around 7.17 dBi. The higher frequency band is generated by the feed patch and the slot whereas lower resonant frequency band is generated by the stub loaded on the slot. The measured results are in a good agreement with the simulated results. The proposed design is suitable for the International Telecommunications Union sub 6 GHz applications.