MIMO Antenna Array Research Articles

Massive metamaterial system-loaded MIMO antenna array for 5G base stations

An integrated massive multiple-input multiple-output (mMIMO) antenna system loaded with metamaterial (MTM) is proposed in this article for fifth-generation (5G) applications. Besides, achievement of duple negative (DNG) characteristics using a proposed compact complementary split-ring resonator (SRR), a broad epsilon negative metamaterial (ENG) with more than 1 GHz bandwidth (BW), and near-zero refractive index (NZRI) features are presented. The proposed mMIMO antenna consists of eight subarrays with three layers that operate in the 5G mind band at 3.5 GHz (3.40–3.65 GHz) with high port isolation between adjacent antenna elements compared to an antenna that does not use MTM. Each subarray has two patches on the top layer, while the middle and bottom layers have two categories of full and partial ground plans, respectively. Simulated, produced, and tested are 32 elements with a total volume of 184 × 340 × 1.575 mm3. The measured findings reveal that the sub-6 antenna has a better than 10 dB reflection coefficient (S11), a lower than 35 dB isolation, and a peak gain of 10.6 dBi for each subarray. Furthermore, the recommended antenna loaded with MTM has demonstrated good MIMO performance with an ECC of less than 0.0001, total efficiencies of more than 90%, more than 300 MHz bandwidth, and an overall gain of 19.5 dBi.

High Gain and Bandwidth Array Antenna for Satellite Application

A MIMO array antenna with a resonance frequency of 12.29 GHz is proposed for Ku-band applications. An 8-element antenna array is proposed and parameters like as return loss, VSWR, gain, directivity, and radiated power are utilized to validate model and test findings. The proposed antenna array has a bandwidth of 136.4MHz and the maximum gain in the Ku Band at a resonance frequency of 12.29GHz. It also has a gain of 8.89 dBi and a radiation efficiency of 100%.

Efficient Online Data-Driven Enhanced-XGBoost Method for Antenna Optimization

The tremendous progress in artificial intelligence promotes the wide application of machine learning (ML) technology in the field of electronic science. Recently ML-based antenna optimization provides a distinct candidate and attracts considerable attention. However, the large number of training samples generated through time-consuming EM simulations becomes a significant challenge. In this article, an efficient online data-driven enhanced-XGBoost (E-XGBoost) method for antenna optimization is proposed, which is mainly composed of two parts, i.e., an input variable filter module (IVFM) and an antenna optimization module (AOM). Specifically, IVFM serves as a variable sensitivity analyzer, which is accomplished by E-XGBoost to efficiently reduce the dimension of design variable and hence save the training samples. Next, the design variables obtained by IVFM are fed into AOM to find the near-optimal solution. In AOM, an online learning strategy is proposed to train a local E-XGBoost model to evaluate the population in the metaheuristic optimization algorithm (MOA). Compared to the global ML model that can mimic the entire design space, this local E-XGBoost model can further cut down the training samples. To verify the performance of the proposed method, several different antenna examples, i.e., U-slot patch antenna, Fabry–Perot resonant antenna, and dual-polarized cross dipole antenna and 5G MIMO antenna array, are simulated. Numerical results support the proposed method in terms of its superior performance and potential advantage of saving computational overhead.

Embedded two dimensional metamaterial structure in MIMO antenna array for mutual coupling reduction

Embedded two dimensional metamaterial structure in MIMO antenna array for mutual coupling reduction

Survey on design and analysis of MIMO antenna array for 5G application

This paper is a Survey on Design and Analysis of MIMO Antenna Array for 5G Application. 5G is evolving as a technology that will employ both low and high frequencies. The Indian government has taken steps to make the 5G vision a reality. The impact of 5G in India on exponential data usage increase was examined. It goes over the 5G specifications that must be met in order to create a 5G system. Mobile network capabilities are rapidly expanding, driven by new requirements such as latency, traffic volumes, data speeds, and the need for consistent connectivity. Advanced antenna systems (AAS) provide cutting-edge beam shaping and MIMO techniques, which are useful for enhancing end-user experience, capacity, and coverage.

Multiband Handset Antenna System for UMTS/LTE/WLAN/Sub-6 5G and mmWave 5G Future Smartphones

In this paper, a new antenna system for rapidly emerging multifunction devices is presented. The proposed antenna system consists of four antenna components each one operating at different frequency bands separately. The designed antennas are isolated and integrated on a single substrate. The first antenna is designed to operate at 1920–2170 MHz covering the UMTS band, whereas the second antenna is proposed for the lower band 5G systems and WiMAX operating within the frequency range of 3.4–4.2 GHz. Furthermore, another antenna is designed to cover the higher band 5G system and the IEEE 820.11a WLAN within the frequency range of 5.1–5.85 GHz. Finally, a 28 GHz bowtie-based MIMO antenna array is designed and simulated for the mmWave future 5G mobile networks. The proposed antennas were designed and simulated by using CST microwave studio. The results showed that all of the proposed antennas exhibited excellent reflection characteristics below −20 dB at the resonant frequency and achieved high radiation efficiency reached 99% in some cases with a peak gain ranging between 4–6 dBi. The proposed antenna system helps smartphones to perform multitasks and achieve a better-quality operation especially with the enormous growth of IoT techniques.

Dual-Band 10-Element MIMO Array for 5G Smartphones in Sub-6 GHz

The dramatic growth of mobile users, IoT-based applications, and astounding channel capacity requirements to connect trillions of devices are some huge challenges of the previous mobile generations, 5G turned up the key solution. Although the 5G MIMO can boost channel capacity and spectrum efficiency, it is very challenging to integrate multiple antennas into a mobile phone with limited space. Therefore, we presented a multi-band 10-elements array antenna operating at the LTE (long term evolution) 42, 43, and 46 frequency spectrum (sub-6 GHz band) for MIMO applications in fourth/fifth generation (4G/5G) modern mobile phones in this paper. A simple T-shaped slot antenna is designed to acquire 10-element MIMO antenna implementation in LTE 42/43 and 46 bands. The presented antenna array is integrated using a low-priced FR-4 substrate which is typically used for 5.7- 6-inch smartphones and possesses dimensions of 150mm × 80mm × 0.8mm. The simulated results show superb impedance matching and isolation between ports (> -12 dB), radiation efficiency (>70 %), and Envelope Correlation Coefficient (ECC< 0.05) over the operational frequency. Consequently, the designed MIMO antenna array is effectively favorable for the 5G MIMO smartphone to enhance data output and the spectrum efficiency.

A high isolation dual-polarized antenna array with coplanar parasitic decoupling wall

A wideband dual-element dual-polarized stacked MIMO antenna array with high isolation is proposed using a coplanar parasitic decoupling wall (CPDW). The CPDW is constructed using a negative permittivity metamaterial array that works at the operating band of the antenna elements. Then, the CPDW is inserted between MIMO antenna elements to block the propagation of the coupling waves. The simulated and measured results are presented to verify the effectiveness of the CPDW. The devised wideband dual-element dual-polarized MIMO antenna array operates in the bandwidth of 4.2–4.9 GHz with high isolation of less than −25 dB, and its radiation patterns are almost unchanged without and with loading the CPDW.

MIMO Antenna with Isolation Enrichment for 5G Mobile Information

A wideband eight-input MIMO array antenna for a fifth-generation smartphone with high enhancement in element segregation is presented. The designed MIMO antenna array comprises eight E-shaped and inverted I-shaped slots on the material with good electrical and thermal conductivity, usually metal. To intensify the bandwidth, the required resonances can be obtained by adjusting the E-shaped slots. Furthermore, to boost the element shielding of the MIMO array antenna system, a single-ended spanner-shaped slot is introduced between each antenna element. As a result, all the elements can cover a wide bandwidth with a frequency range of 3.3 GHz to 6 GHz. The isolation is boosted to 20 dB by a single-ended spanner-shaped slot, and the ECC below 0.04 is measured between any two elements, which show agreeable impedance in far zone radiation characteristics. In the proposed system design, the coupling is induced by the current over a surface on a metallic frame between two antenna components. Consequently, two elements of antenna were separated with an etched slot engraved on a metal frame and used a unique wrench-like resonator to limit the surface current; even though this arrangement increases the free surface of the antenna, it can effectively reinforce the insulation of the element. The performance of the proposed system analyzed certain antenna radiations by handset and head versions. As a consequence, the efficiencies of antennas 2, 3, and 5 are less than 60%, the efficiencies of antenna 8 are around 60%, and the efficiencies of antennas 1, 4, 5, 6, and 7 are even more than 60%. The proposed wideband MIMO antenna device demonstrates reasonably good isolation and low envelope correlation coefficient, both of which are pretty good for fifth-generation MIMO antenna application. The calculated findings show that the planned antenna array’s operating frequency range is capable of covering 3.3 to 6 GHz, with over 20 dB isolation. The antenna will guarantee that the ECC level is smaller than 0.04. The proposed MIMO antenna technology is also efficient for mobile terminal 5G applications.

5G base station antenna integrated into solar panel

The article discusses the development of a MIMO antenna array for networks of the fifth generation of millimeter wave ultra-wideband data transmission. The antenna system is designed to form base stations that are integrated into solar panels designed to generate electricity for backup power supply of network equipment or for other consumers. Implementation of the antenna array based on the proposed design allows for beam formation and control of the direction of radiation due to synchronous feeding of antenna elements with different phases. When forming a linear antenna array of four antenna elements, it is possible to achieve antenna beam control within the range from -30 to 30 degrees; when forming an array of 2x2 elements, the antenna beam is controlled in two directions, while the deflection range is from -20 to 20 degrees.

A non-uniform strip-array decoupling structure of the MIMO antenna-arrays for the DSRC application

ABSTRACT In this paper, a non-uniform strip-array decoupling structure (SADS) of the MIMO antenna-arrays for the dedicated short-range communication (DSRC) applications in intelligent transportation systems (ITS) is presented. The SADS is composed of metal strips with non-uniform longitudinal layout, which has a simple strip-array geometry, low design and fabrication complexity, and easy to be applied to the design domain without destroying the original antenna-array. The design of the strip thickness, strip-array layout and number of strips is realised by the proposed simple and effective optimisation method. The mutual coupling between the elements can be effectively suppressed to less than −32 dB by the proposed structure in the required bandwidth (5.795 GHz~5.815 GHz). The results show that, compared with the no-strip and uniform SADS, the non-uniform SADS can improve the maximum mutual coupling reduction by 23 dB and 13 dB, respectively. Both the simulated and measured results verify the effectiveness of the proposed SADS, which makes it very suitable for the large-scale MIMO antenna-arrays.

Mutual Decoupling for Massive MIMO Antenna Arrays by Using Triple-Layer Meta-Surface

The high isolation massive antenna arrays are the key devices in the base station of the future wireless communication systems. The challenge for the array application is how to reduce the coupling among the array elements. This paper introduces a new decoupling method for massive MIMO arrays with an innerelement distance of around half wavelength by using a triple-layer metasurface (TMS). The TMS comprises three identical surfaces. The waves reflected from the bottom metasurface (MS) and top two-layer MS have the same amplitudes and the opposite phases, which are canceled with each other. An example of 4×4 dualpolarized wideband microstrip array with a TMS is proposed to verify the decoupling method. The simulation and measurement show that the TMS can help reduce the coupling among the array elements to less than -24 dB in both the co-polarization and cross-polarization directions within 4.23-4.82 GHz. In the meanwhile, the radiation characteristics of the arrays with and without TMS are almost unchanged.

A Modified SWB Hexagonal Fractal Spatial Diversity Antenna With High Isolation Using Meander Line Approach

This manuscript introduces a novel miniaturized super wideband (SWB) hexagonal fractal spatial diversity 2-element multiple-input-multiple-output (MIMO) antenna for broadband applications, as a compact wideband antenna is required for military radio and space communication devices. The designed antenna includes two hexagonal ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1^{st}$ </tex-math></inline-formula> modified Koch iteration) Koch fractal radiators with two linear tapered feedlines (TLTF) and a step tapered slotted ground plane (STSGP) that provides the broad impedance characteristic with miniaturized size in the operating band of 1.78-30 GHz. Moreover, the STSGP is also accountable for enabling the isolation ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$S_{12/21}$ </tex-math></inline-formula> ) better than 10 dB. To further meet the isolation higher than 22 dB, a meander line is protruded from the ground plane while maintaining a 6 mm edge-to-edge distance between two antenna elements. Typically, the MIMO antenna with high isolation is beneficial for high-speed data transmission. The experimental outcomes represent that the proposed MIMO antenna is with the advantages of reasonably good diversity gain (nearly 10 dB), stable radiation patterns, high peak gain (almost 6.6 dBi), and moderate radiation efficiency (around 85%) across -10 dB impedance bandwidth. The total active reflection coefficient (TARC) and envelop correlation coefficient (ECC) are less than −25 dB and 0.1 respectively. Due to all these attributes, the proposed 2-element MIMO antenna array can be a potential candidate for military radio, spectrum sensing for cognitive radio, and space communication applications.

Thru-the-wall Eavesdropping on Loudspeakers via RFID by Capturing Sub-mm Level Vibration

The unprecedented success of speech recognition methods has stimulated the wide usage of intelligent audio systems, which provides new attack opportunities for stealing the user privacy through eavesdropping on the loudspeakers. Effective eavesdropping methods employ a high-speed camera, relying on LOS to measure object vibrations, or utilize WiFi MIMO antenna array, requiring to eavesdrop in quiet environments. In this paper, we explore the possibility of eavesdropping on the loudspeaker based on COTS RFID tags, which are prevalently deployed in many corners of our daily lives. We propose Tag-Bug that focuses on the human voice with complex frequency bands and performs the thru-the-wall eavesdropping on the loudspeaker by capturing sub-mm level vibration. Tag-Bug extracts sound characteristics through two means: (1) Vibration effect, where a tag directly vibrates caused by sounds; (2) Reflection effect, where a tag does not vibrate but senses the reflection signals from nearby vibrating objects. To amplify the influence of vibration signals, we design a new signal feature referred as Modulated Signal Difference (MSD) to reconstruct the sound from RF-signals. To improve the quality of the reconstructed sound for human voice recognition, we apply a Conditional Generative Adversarial Network (CGAN) to recover the full-frequency band from the partial-frequency band of the reconstructed sound. Extensive experiments on the USRP platform show that Tag-Bug can successfully capture the monotone sound when the loudness is larger than 60dB. Tag-Bug can efficiently recognize the numbers of human voice with 95.3%, 85.3% and 87.5% precision in the free-space eavesdropping, thru-the-brick-wall eavesdropping and thru-the-insulating-glass eavesdropping, respectively. Tag-Bug can also accurately recognize the letters with 87% precision in the free-space eavesdropping.

Decoupling of 2 × 2 MIMO Antenna by Using Mixed Radiation Modes and Novel Patch Element Design

This article presents a novel and simple method for the decoupling of a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times 2$ </tex-math></inline-formula> MIMO antenna array. Two distinct radiation modes, with different patterns and polarizations, are created by a novel patch element design. This new configuration enables the excitation of additional coupling paths between antennas, and ultimately the neutralization of mutual coupling. Since the two radiating modes are generated by the same patch element, the proposed MIMO antenna also features simple structure and compact size. For verification, a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times 2$ </tex-math></inline-formula> MIMO antenna with center-to-center spacing of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.475\lambda _{0}$ </tex-math></inline-formula> is prototyped and characterized. Simulation and experimental results reveal that the proposed design can offer enhanced port isolation, antenna efficiency, and pattern diversity.

Metasurface-based coupling suppression for wideband multiple-input-multiple-output antenna arrays

Wideband decoupling requires simultaneous improvements in the performance of an antenna array in its operating band. In this paper, a metasurface structure is proposed to accomplish this difficult task in wideband dual-layer coupled patch multiple-input-multiple-output (MIMO) antenna arrays. The decoupling mechanism is analyzed based on network and field theories, and dual-band response is achieved by incorporating multilayer hybrid split-ring resonators to create a meta-atom equipped with single negative property. By introducing the metasurface into the H-plane coupled MIMO array, the working bandwidth improves from 21.7% to 25.4%, mutual coupling is suppressed to less than −20 dB, gains mostly improve, and radiation patterns are modified. Moreover, the metasurface-based decoupling structure is extended to the E-plane coupled and two-dimensional arrays, exhibiting the same decoupling capability in the 22.9% and 23.6% bandwidths, respectively. Compared with existing metasurface-based decoupling works, the proposed metasurface, which is designed to be coplanar with the array, brings about no change to the array profile and possesses a wider decoupling bandwidth. These results indicate its potential in efficiently decoupling multielement wideband MIMO antenna arrays.

Active Patch Antenna for Wi-Fi 5, 6 and Wi-Fi 6E Applications

The article discusses a planar patch antenna with a metamaterial integrated into the structure, which allows the antenna to function in the upper Wi-Fi 5, 6 frequency range and the Wi-Fi 6E range. For the study, we built graphs of S-parameters, radiation patterns; on the basis of the resulting structure, we formed a MIMO antenna array for which we determined the main characteristics - the envelope correlation coefficient and the multiplexing efficiency

Efficient and optimized six- port MIMO antenna system for 5G smartphones

AbstractIn this paper, six-port MIMO antenna is presented for 5G mobile handsets. The proposed six-port antenna array is designed by making four L shaped monopole slots at four corners and two at the middle side edges of the ground plane which is printed on the backside of 0.8 mm thick FR4 substrate. High isolation (&gt;−18 dB) between any pair of antenna elements is achieved without deploying dedicated isolation enhancing mechanisms. The antenna is working from 3.4–3.6 GHz (LTE Band 42) with 200 MHz bandwidth in the 2:1 VSWR (−10 dB impedance bandwidth). The proposed six-port MIMO antenna array is fabricated and measured. Significant radiation efficiency is obtained from 70 to 74 % in desired band of operation. Further, the MIMO parameters such as Envelope Correlation Co-efficient (ECC), Channel Capacity, Channel Capacity Loss (CLL) and Total Active Reflection Co-Efficient (TARC) are calculated. The robustness of the antenna is estimated by analyzing the user hand effects and Specific Absorption Rate (SAR). The measured results are well agreed with the simulated results.

A matrix-based design of broadband low-profile isolation and matching circuit for compact Wi-Fi/WLAN MIMO antenna arrays

A novel microstrip network is proposed for simultaneously controlling and improving the isolation and impedance matching in a highly-coupled printed monopole antenna array. This easy-to-fabricate network with a reduced number of key parameters including only an inductive microstrip line between two feeds, some functional simple links and two shorted stubs is designed in a small area. A matrix-based study on the total system along with an equivalent analysis method on the subsystem is presented to simplify the total study, noticeably. Network-based closed-form equations for real and imaginary parts of the self and mutual admittance of the antennas are extracted to establish the conditions and determine the parameters. A good agreement between the simulation and measurement of the prototypes is also provided. The results propose a broad bandwidth about 200 MHz at 2.45 GHz with an improved matching over 15 dB from 2.39 to 2.5 GHz. In this band, the isolation is improved over 32 dB with a maximum of about 70 dB. Using this network, not only good space diversity and high polarization purity are achieved, but also the correlation coefficient is reduced, notably. According to these suitable specifications, this efficient circuit can be a promising design for new compact MIMO-based Wi-Fi/Bluetooth/WLAN systems.

Reduction of Mutual Coupling in UWB/MIMO Antenna Using Stub Loading Technique

Abstract The research presents mutual coupling reduction between UWB-MIMO antenna elements using stub loading technique. The proposed 2 × 2 UWB antenna geometry consists of two circular-shaped monopole radiators with a partial ground for perfect impedance matching. Stubs of 20 mm × 0.2 mm are inserted between the two antenna elements in the ground plane to improve the isolation. The decoupling stub leads to a mutual coupling reduction of less than 20 dB. The farfield measurement at a selected frequency of 10 GHz confirms an omnidirectional radiation pattern. Different MIMO antenna metric such as channel capacity loss (CCL), mean effective gain (MEG), total active reflection coefficient (TARC), envelope correlation coefficient (ECC), and surface current are presented. Details of the design considerations and the simulation and measurement results are presented and discussed. The proposed MIMO antenna array can be well suited for UWB applications.