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This article presents a quad-element MIMO antenna designed for multiband operation. The prototype of the design is fabricated and utilizes a vector network analyzer (VNA-AV3672D) to measure the S-parameters. The proposed antenna is capable of operating across three broad frequency bands: 3–15.5 GHz, encompassing the C band (4–8 GHz), X band (8–12.4 GHz), and a significant portion of the Ku band (12.4–15.5 GHz). Additionally, it covers two mm-wave bands, specifically 26.4–34.3 GHz and 36.1–48.9 GHz, which corresponds to 86% of the Ka-band (27–40 GHz). To enhance its performance, the design incorporates a partial ground plane and a top patch featuring a dual-sided reverse 3-stage stair and a straight stick symmetrically placed at the bottom. The introduction of a defected ground structure (DGS) on the ground plane serves to provide a wideband response. The DGS on the ground plane plays a crucial role in improving the electromagnetic interaction between the grounding surface and the top patch, contributing to the wideband characteristics of the antenna. The dimensions of the proposed MIMO antenna are 31.7 mm × 31.7 mm × 1.6 mm. Furthermore, the article delves into the assessment of various performance metrics related to antenna diversity, such as ECC, DG, TARC, MEG, CCL, and channel capacity, with corresponding values of 0.11, 8.87 dB, −6.6 dB, ±3 dB, 0.32 bits/sec/Hz, and 18.44 bits/sec/Hz, respectively. Additionally, the equivalent circuit analysis of the MIMO system is explored in the article. It’s worth noting that the measured results exhibit a strong level of agreement with the simulated results, indicating the reliability of the proposed design. The MIMO antenna’s ability to exhibit multiband response, good diversity performance, and consistent channel capacity across various frequency bands renders it highly suitable for integration into multi-band wireless devices. The developed MIMO system should be applicable on n77/n78/n79 5G NR (3.3–5 GHz); WLAN (4.9–5.725 GHz); Wi-Fi (5.15–5.85 GHz); LTE5537.5 (5.15–5.925 GHz); WiMAX (5.25–5.85 GHz); WLAN (5.725–5.875 GHz); long-distance radio telecommunication (4–8 GHz; C-band); satellite, radar, space communications and terrestrial broadband (8–12 GHz; X-band); and various satellite communications (27–40 GHz; Ka-band).

This paper presents a multiple-input multiple-output (MIMO) antenna system for millimeter-wave 5G wireless communication services. The proposed MIMO configuration is composed of four antenna elements, where each antenna possesses an HP-shaped configuration that features simple configuration and excellent performance. The proposed MIMO design can operate at a very wideband of 36.83–40.0 GHz (measured). Furthermore, the proposed MIMO antenna attains a peak gain of 6.5 dB with a maximum element-isolation of −45 dB. Apart from this, the MIMO performance metrics such as envelope correlation coefficient (ECC), diversity gain, and channel capacity (CCL) are analyzed, which demonstrate good characteristics across the operating band. The proposed antenna radiates efficiently with a radiation efficiency of above 80% at the desired frequency band which makes it a potential contender for the upcoming communication applications. The proposed design simulations were performed in the computer simulation technology (CST) software, and measured results reveal good agreement with the simulated one.

Classical information theory (CIT) characterizes the transmission limit for communication systems under syntactic accuracy, whereas semantic information theory (SIT) studies communication from the perspective of semantic fidelity induced by synonymous mapping. In this paper, we investigate the semantic channel capacity of Rayleigh fading channels under synonymous mapping of the channel gain and additive noise. We first derive the semantic capacity formula when synonymous mapping is applied to the channel fading coefficient and establish corresponding upper and lower bounds using Jensen’s inequality. To determine an optimized synonymous partition, the partition design is formulated as a constrained optimization problem and solved numerically using a neural network-based approach with the Adam optimizer. Furthermore, we extend the framework by applying synonymous mapping to both the channel fading coefficient and the additive noise and derive the corresponding semantic capacity formula together with its theoretical bounds. The numerical results illustrate the theoretical semantic channel capacity under synonymous mapping and validate the compatibility of the proposed framework with both CIT and SIT. At a 20-dB SNR with K=8 channel gain intervals and J=4 noise intervals, the semantic capacity reached 9.86 sebits/s/Hz.

In this paper, we consider α-κ-µ-Extreme/gamma composite fading channel model, which is used to characterize non-linear severe fading and shadowing impairments in enclosed wireless propagation scenarios. For this model, we first obtain the probability density function (PDF) expression for the received signal-to-noise ratio(SNR). Using the derived PDF, throughput analysis is provided by deriving expressions for the average channel capacity(ACC) and effective capacity(EC) in closed-form. The derived expressions are evaluated for several values of fading and shadowing indexes to study their effect on the ACC and EC. Furthermore, asymptotic analysis of ACC and EC are carried out to show better approximation under the high and low SNR regimes.

Mutual coupling between the multiple antenna designs is a critical problem which deteriorates the performance of multiple input multiple output (MIMO) system. It affects the antenna efficiency and influences the correlation. In this paper, a study on the isolation between the multiple antenna elements is presented. The antennas are placed on a cost-effective compact dielectric substrate with different orientations to minimize the correlation. A CPW fed antenna is designed using FR4 substrate, using which two and four element antenna structures are developed. The performance parameters are analysed, wherein the envelope correlation coefficient (ECC) has to be less than 0.5, diversity gain nearer to 10 dB in the operating bandwidth, mean effective gain (MEG) less than 3 dB, channel capacity loss (CCL) less than 0.4 bits/s/Hz and the isolation between the antenna elements well above 20 dB. Acceptable gain, high radiation efficiency, and stable radiation pattern of the proposed design are analysed and the fabricated prototype of two and four element is measured for its performance parameters. All the necessary simulations are carried out in the EM simulator Ansys HFSS v.14.0 and a detailed comparison study is done based on the existing antennas.

This article presents a compact Co-Planar Waveguide (CPW) fed antenna for next-generation Vehicular Communications. The antenna is designed by employing two rectangular stacked patch structures and slots, making the antenna resonate at dual frequency bands. The analytical study of antenna design is carried out using the governing microstrip patch equations. On optimizing the patch's dimensions for CPW structures, the desired frequency range of operation is obtained for the single element antenna structure. The designed antenna resonates at 3.5 GHz (LTE-42 Band) and 5.9 GHz (DSRC Band), yielding this antenna to be a prime component for Vehicular to Everything (V2X) Communication. The optimized single-element antenna structure is 35 mm × 20 mm designed on an FR-4 substrate of thickness 1.6 mm. The substrate has a dielectric constant of 4.4 and a loss tangent value of 0.001. Further, the antenna structure is developed as a 4-element MIMO configuration with the distance between adjacent antenna elements to be 10 mm. The adjacent antennas in the MIMO configuration are positioned orthogonal to each other, thereby exhibiting better isolation between the antenna elements. The antenna has a reflection coefficient value of < −10 dB within the bandwidth of interest and VSWR less than 2. The Gain value of the designed antenna ranges between 2.8 and 2.9 dBi at 3.5 GHz and between 3.6 and 3.7 dBi at 5.89 GHz. The overall efficiency of the antenna element is between 60 and 80% at both frequency bands. MIMO parameters are analyzed by calculating the Channel Capacity Loss (CL), Diversity Gain (DG), Envelope Correlation Coefficient (ECC) and Total Active Reflection Co-Efficient (TARC). The designed antenna is fabricated and tested, which shows the measured results coincide with the simulated antenna results. The overall dimension of the MIMO configured antenna design is 60 mm × 60 mm × 1.6 mm, which is highly compact and is a suitable candidate for deployment of Vehicle to Vehicle (V2V), Vehicle to Infrastructure (V2I), and Vehicle to Network (V2N) scenarios.

A compact four-element dual-band multiple-input and multiple-output (MIMO) antenna system is proposed to achieve high isolation and low channel capacity loss. The MIMO antenna was designed and optimized to cover the dual-frequency bands; the first frequency band is a wide band, and it covers the frequency range of 1550–2650 MHz, while the other frequency band covers the 3350–3650 MHz range. The measured wide-band impedance bandwidths of 1.1 GHz and 300 MHz were achieved in the lower and upper frequency bands, respectively. The proposed structure consists of four novel antenna elements, along with a plus-sign-shaped ground structure on an FR4 substrate. The overall electrical size of the whole dual-band MIMO antenna system is 0.3λ(W) × 0.3λ(L) × 0.008λ(H) for the lower frequency band. It achieved greater than 10 and 19 dB isolation in the lower and upper frequency bands, respectively. The antenna system accomplished an envelope correlation coefficient of |ρ|≤0.08 in the lower frequency band, while it achieved |ρ|≤0.02 in the higher frequency band. The computed channel capacity loss remained less than almost 0.4 bits/s/Hz in both frequency bands. Therefore, it achieved good performance in both frequency bands, with the additional advantage of a compact size. The proposed MIMO antenna is suitable for compact handheld devices and smartphones used for GSM (Global System for Mobiles), UMTS (Universal Mobile Telecommunications Service), WCDMA (Wideband Code Division Multiple Access), LTE (Long Term Evolution), 5G sub-6 GHz, PCS (Personal Communications Service), and WLAN (wireless local area network) applications.

This study introduces a compact plant-structured MIMO antenna developed for modern wireless applications, including Wi-Fi 6E and IoT Systems. The design structure is implemented on substrate of FR-4 with a small footprint as 45 mm 20 mm, which makes it well suited for miniaturized wireless devices. The antenna resonates at 6.98 GHz with IBW of 1.8 GHz (5.5-7.3 GHz) effectively covering the upper C-band band for Wi-Fi 6E and IoT Systems. The achieved simulated S11 result of − 19.33 dB verifies good matching of impedance characteristics. The mutual coupling within MIMO elements is limited to − 19.89 dB (S21) demonstrating efficient isolation performance. An inter-element spacing of 6.5 mm is preserved to further minimize electromagnetic interaction. Important MIMO performance indicators such as Total Active type Reflection Coefficient (TARC), Channel type Capacity Loss (CCL), Diversity related Gain (DG) and Envelope Correlation type Coefficient (ECC) are comprehensively analyzed. All evaluated MIMO parameters remain within the standard acceptable limits confirming dependable wireless system operation. The obtained results reveal excellent diversity behavior, minimal correlation and enhanced channel capacity. Therefore, designed plant-structured MIMO system serves as a strong for compact, efficient and reliable for Wi-Fi 6E and IoT Systems.

In this paper, a modified nonagonal monopole antenna-based four-port compact MIMO antenna is presented for ultra-wideband (UWB) applications. The modification of the regular nonagonal shape is performed in order to ensure the coverage of complete UWB band. The current MIMO structure operates on a frequency range of 2.96–13.2 GHz with − 10 dB impedance bandwidth of 10.24 GHz. The overall dimension of the proposed MIMO antenna is 56 × 56 × 1.6 mm 3 , whereas its corresponding patch dimension is 26 × 20 mm 2 . The prototype of four-element array antenna is fabricated and measured. It is observed that a significant isolation is achieved over the complete UWB band with a minimum isolation of 15 dB making the proposed design well equipped for UWB applications. The novelty of the current MIMO system is improved the fractional bandwidth and port isolation can be achieved with Defected Ground Structure without using complex structures. MIMO antenna parameters like Envelope Correlation Coefficient, Diversity Gain, Total Active Reflection Coefficient, Channel Capacity Loss, and Mean Effective Gain are measured. The values of the MIMO parameters are within the accepted threshold limits.

Badarneh and da Costa (IEEE Wirel Commun Lett, 2024. https://doi.org/10.1109/LWC.2024.3353620 ) introduced the fluctuating fading distribution by taking the signal envelope to be the ratio of two independent random variables, one having the Nakagami m distribution and the other a uniform random variable. The Nakagami m distribution corresponds to signals following the normal distribution which may not always hold in practice. In this paper, we derive twenty other fluctuating fading distributions. For each distribution, we give explicit expressions for the average channel capacity and the average bit error rate. Their correctness is checked numerically.