Mutual Coupling Effects Research Articles

Hybridization of almost difference sets and DFT technique for concentric circular antenna array thinning

This paper introduces a hybrid methodology for minimizing the peak sidelobe level (PSLL) in concentric circular antenna arrays (CCAAs). Traditionally, the almost difference set (ADS) approach has been utilized for determining active element positions, but its effectiveness in PSLL reduction is limited. To address this limitation, the proposed methodology integrates the ADS approach with the discrete Fourier transform (DFT) technique. This integration optimizes excitation amplitudes for activated elements within the ADS-based thinned array, resulting in significant PSLL reduction. Simulation results across various case studies demonstrate that the hybrid ADS-DFT method achieves lower PSLL values than existing thinning techniques while maintaining high computational efficiency. Additionally, electromagnetic (EM) simulations validate the efficiency of the proposed method, considering mutual coupling effects.

Study on Winding Design of Dual Three-Phase Electrical Machines for Circulating Current Harmonics and Vibration Suppression

The dual three-phase electrical machines (DTP-EMs) have significant advantages and application potential in large-power and high reliability electromagnetic drive system. Nevertheless, one of the main operating challenges of DTP-EMs is the significant high-frequency circulating current harmonics when supplied with voltage-source inverters (VSIs), which will bring unexpected vibration and loss. This paper provides a thorough study on the mutual magnetic coupling effect and design criterion of dual three-phase winding. First, the mathematical model of DTP-EMs is established. Then, the internal mechanism of mutual magnetic coupling and the relationship among the mutual leakage inductance in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$x$</tex-math></inline-formula> - <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$y$</tex-math></inline-formula> subspace, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\alpha$</tex-math></inline-formula> - <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\beta$</tex-math></inline-formula> subspace and stator leakage inductance is revealed. Furthermore, the winding design criterion for DTP-EMs considering high-frequency circulating current harmonics and vibration suppression is proposed. It is drawn that full pitch is required for DTP-EMs to minimize the high-frequency current harmonics and vibration. Finally, two prototypes of the DTP-EM are built and tested to validate the theoretical analysis. This paper provides an effective winding design guide of DTP-EMs for the high-frequency current harmonics suppression and can also be expand to other multi-phase machines.

Semi-symmetrical Coprime Linear Array with Reduced Mutual Coupling Effect and High Degrees of Freedom

Semi-symmetrical Coprime Linear Array with Reduced Mutual Coupling Effect and High Degrees of Freedom

Low-coupling reflective metasurfaces for accurate near-field focusing

Metasurface is a 2D metamaterial which manipulates electromagnetic wavefront by carefully designing the transmissive or reflective responses of the planar subwavelength structures. Despite various emerging new functionalities, one of the limitations of metasurfaces in practical applications is the lack of control accuracy of its local amplitude and phase responses. This is in part caused by the discrepancy between the periodic EM simulated responses of unit cells and the actual non-periodic metasurfaces when functionality-determined amplitude and phase gradients are introduced. Under such conditions, the focusing capabilities of metasurfaces can be greatly affected. In this paper, we address this problem by introducing a slotted ground plane metasurface design which reduces the above-mentioned discrepancy by limiting the mutual coupling effects of a unit cell with its surrounding elements. An offset-fed near-field focusing reflective metasurface is designed and fabricated to verify the performance of the proposed design. Both the EM simulated and measurement results demonstrate the advantages of the proposed design in terms of sidelobe level and transfer efficiency.

Compact body‐worn MIMO antenna with high port isolation for UWB applications

SummaryThis article investigates the mutual coupling reduction of a compact two elements wearable ultra‐wideband (UWB) multiple‐input multiple‐output (MIMO) antenna. The ground plane of the proposed wearable MIMO antenna structure consists of three connected square ring‐shaped stubs and two rectangular slots of narrow height. These ground stubs and slots minimize the mutual coupling effect between antennas and provide high isolation. The suggested MIMO antenna functions from the 1.87 to 13.82 GHz frequency spectrum covering WLAN (2.4–2.484 GHz), UWB (3.1–10.6 GHz), and X band (8–12 GHz) with 152.32% fractional bandwidth. It sustains port isolation above 27 dB throughout the 2 to 13.82 GHz frequency band. Inside the whole working frequency band, the suggested antenna offers a tiny envelope correlation coefficient (ECC &lt; 0.098), greater diversity gain (DG &gt; 9.93 dB), minimum channel capacity loss (CCL &lt; 0.32 bits/s/Hz), and slight magnitude variation in mean effective gain of antenna ports (&lt; 0.1 dB). The recommended antenna yields a SAR level below the designated threshold (&lt;1.6 W/kg), affirming its suitability for body‐worn applications. The designed MIMO antenna structure has an overall volume of 32 × 48 × 1.5 mm3.

Analysis of following vehicle driver injury severity in rear-end collision on straight road based on LightGBM and SHAP

Rear-end accidents, as one of the common accident types, may cause serious injuries to the driver and passengers. There are mutual coupling effects among causal features of rear-end accidents, and traditional analytical methods may lead to modeling distortion due to assumption constraints. In this study, the Light Gradient Boosting Machine (LightGBM), a machine learning algorithm, is used to model the injury severity of the following vehicle driver in a rear-end crash accident on a straight road, based on the data from the China In-depth Accident Study data. The Shapley Additive Explanations (SHAP) method was used to interpret the results of the LightGBM model and to analyze the relationship between factors and driver injury severity. The results show that location familiarity, willingness to take risks, and driving time have a significant impact on the injury severity for following vehicle drivers involved in rear-end crashes. Cloudy conditions increase a driver’s risk of being involved in a fatal or injured rear-end collision. In rain, snow, hail, and foggy conditions, have a higher propensity to cause driver fatalities in the crash event. The rear-end crash of passenger cars resulted in a higher death probability of the following vehicle driver compared to sedan and truck, and female drivers are more likely to be involved in uninjured accidents compared to males. These results are informative for preventing rear-end accidents and reducing the extent of accidental injuries.

Mitigating mutual coupling effects on circular polarization for improved bandwidth in MIMO systems: A novel approach

An improved mutual coupling compensation in circularly polarized (CP) multi-input multi-output (MIMO) dielectric resonator antenna (DRA) is presented in this paper. Using trimming approach, the mutual coupling (MC) between closely spaced DRA units at 0.3λ has been significantly reduced while axial ratio performance has been maintained. Mutual coupling reduction is obtained by trimming the DRA to ensure low mutual coupling below −20dB. The exclusive features of the proposed MIMO DRA include wide impedance matching bandwidth (BW), triple band circular polarization, and suppressed MC between the radiating elements. The impedance bandwidth matches perfectly with a triple band's 3 dB axial ratio (AR). It is designed with characteristic mode analysis with good agreement of the measurement that has been obtained. Using the probe feed method, the DRA and patch strip are coupled together to allow bandwidth widening of the pro-posed DRA. An impedance bandwidth of 34% at a lower frequency to around 2% at a higher frequency was achieved in all resonance frequencies. Thus, we refer to our newly designed DRA as a proposed method for effectively reducing the mutual coupling between DRAs. Additionally, the 3 dB AR bandwidth matched at 3.3 GHz, 4.6 GHz, and 6.3 GHz with a percentage of 11.66%, 3.04%, and 2.22% obtained at the three different frequencies. Note that the proposed DRA exhibits low mutual coupling (below −20 dB) at the targeted frequencies, which is suitable for better signal reception for MIMO applications. By computing, the metrics envelop correlation coefficient, diversity gain, channel capacity loss, and total active reflection coefficient, the MIMO performance of the proposed antenna is verified. The experiments show a close result between simulated and computed validation of the proposed DRA.

Optimization and analysis of air-to-ground wireless link parameters for UAV mounted adaptable Radar Antenna Array

Unmanned Aerial Vehicles (UAVs) are rapidly used in a variety of applications such as surveillance, search and rescue operation, delivery, etc. These operations strongly depend on the performance of the air-to-ground (A2G) communication link. This link communicates vital information between the UAV and the ground station (GS). However, due to the UAV’s unpredictable mobility, the A2G link becomes unreliable, which limits the quality of data transfer. An Adaptable Radar Antenna Array (ARAA) can be used to solve this problem by effectively handling transmitted data through altering the antenna pattern using the beamforming process. This work proposes a new algorithm for selecting antenna patterns with proper beamforming by considering the effect of wobbling and mutual coupling (MC). In addition, the proposed algorithm is used to reduce the maximum sidelobe level (SLL) and optimize the distance between the interelement of ARAA, which directly controls the MC effect in a time-varying channel. Also, an analysis is done for various antenna configurations, such as Uniform Linear Array (ULA), Uniform Rectangular Array (URA), and Uniform Circular Array (UCA), while varying different UAV parameters like altitude, speed, location error, and beamforming capacity.

Mutual coupling effects in 2×2 antenna array for ground penetrating radar on multilayered soil

&lt;span&gt;Caral stands as the Americas’ oldest city, boasting a heritage spanning 5,000 years. Over time, various natural forces have woven a complex geological stratum. To gain a deeper understanding of the Caral civilization, non-intrusive exploration methodologies like ground penetrating radar (GPR) are beginning to be used. This method safeguards the integrity of ancient subterranean remains. A GPR system is in development, tailored to the &lt;br /&gt; [200-500] MHz range, employing a 2×2 antenna array with dual polarization. These features enhance resolution without compromising penetration depth. However, using multiple antennas within complex, multi-layered environments introduce impedance band constraints and exacerbates antenna coupling issues. This study assesses the coupling of two antenna candidates: the Vivaldi with defected ground structures (DGS) and the log periodic dipole array (LPDA). The scattering parameters show that the LPDA antenna performed better considering measured and simulated data. Cross-polarization exhibited a broader bandwidth in the LPDA antenna, evident in both simulated and measured data. Additionally, a comprehensive comparison of GPR simulations for each antenna type within an 11-level multilayer medium, with different electromagnetic properties, further highlights LPDA. This antenna boasts a 209 MHz bandwidth and a coupling better than -23 dB for the cross-polarization configuration, firmly showing its best performance.&lt;/span&gt;

On line monitoring of transmission line

Continuous online monitoring of transmission line is required for proper functioning of power system. This paper presents two simulink model one for single transmission line, singly fed and the other for parallel transmission line doubly fed and presents the simulation result which shows the continuous variation in transmission line impedance before, during and after the fault. This paper shows the effect of different factors like prefault system condition, ground fault resistance, series compensation effect individually and then taking together on impedance plot under line to ground fault and three phase to ground fault. In case of parallel transmission line the paper have taken into account of mutual coupling effect also.

Multibeam Cylindrical Conformal Array in the Presence of Enhanced Mutual Coupling

The limitations of conventional sensors have made array antennas increasingly crucial for gathering information and communication applications in intelligent transportation and communication systems. Compact cylindrical arrays are particularly favored for their ability to achieve azimuth angle scanning. However, the substantial mutual coupling effect between the elements on curved surfaces and its implication for these arrays remain unclear, which is a key factor to consider when such arrays are used for multibeam applications. This study investigates the effect of mutual coupling in a dual-slant-polarized cylindrical array. The results showed that mutual coupling is predominantly observed among the closely located elements, and it is essential for achieving an ultra-wide bandwidth. The study also analyzes the impact of mutual coupling on the scan impedance and radiation characteristics for multibeam applications and reveals that these arrays exhibit robust multibeam capability, hence having great potential for use in sensing and communication applications.

Shared-radiator design of broadband and dual-mode antenna for personal role radio applications

Abstract Shared-radiator design of a broadband and dual-mode antenna that simultaneously covers the VHF/UHF band and satellite navigation band is presented for personal role radio (PRR) applications. Quadrifilar helix antenna (QHA) is devised to be a circularly polarized radiator which as well acts as a part of the upper half radiation arm of the dipole antenna and be equivalent to a linearly polarized radiation current carrier at VHF/UHF band, forming a symmetrical dipole antenna with a sinusoidal current distribution. A 5th-order balanced matching network comprised of five cascade L-sections is adopted to obtain the maximum possible working band-width and a 3.76:1 band-width (116 %) at VHF/UHF band is achieved. Strong mutual coupling effect of the two operating modes is observed near 1.5 GHz originated from QHA shared-radiator design, and a new balun structure is applied to achieve high isolation and self-decoupling, subsequently |S21| of the two operating modes is significantly reduced from about −18 dB to below −32 dB at satellite navigation band without affecting the reflection coefficient and radiation efficiency. The measured results show that radiation patterns of the manufactured prototype is basically consistent with corresponding simulation counterparts.

The Mitigation of Mutual Coupling Effects in Multi-Beam Echosounder Calibration under Near-Field Conditions

The advancement of unmanned platforms is driving the miniaturization and cost reduction of the multi-beam echosounder (MBES). In the process of MBES array calibration, the mutual coupling significantly impacts the performance of parameter estimation. We propose a correction method to mitigate the mutual coupling effects in the calibration of MBES acoustic array. Initially, a near-field focused beamforming model is established to assess the influence of mutual coupling. Subsequently, the covariance matrix in the frequency domain is constructed to enhance algorithm efficiency and simplify solution procedures. This construction eliminates the need for a low-pass filtering step after heterodyning through extracting peak values near zero frequency in the signal frequency domain. Meanwhile, the Toeplitz property is leveraged to render the estimation results independent of the mutual coupling matrix. Finally, the mutual coupling coefficients and the direction of arrival (DOA) are joint-estimated and the Cramér–Rao bound is derived. The presented method effectively addresses the engineering challenge of MBES mutual coupling calibration. Additionally, the performance of the proposed method is verified through the measured data in simulation and tank experiments.

Migrated coprime array with low mutual coupling for space limited aperture

It is well established that sparse sensor array can estimate more sources than number of sensors exploiting difference coarray. However, the array aperture size is restricted in space limited scenarios and all sensor elements are distributed in limited space. This could raise potential problems due to the mutual coupling effect. To address this issue, a migrated coprime based sparse array configuration is designed considering the following schemes. Enhancing the length of consecutive part in difference coarray while introducing no extra sensor. The mutual coupling level is reduced as low as possible, and the array aperture is also limited to acceptable level to allow possible applications in space limited scenarios. Simulation results elaborate the superiority of proposed strategy from the above aspects.

Direct Observation of the Mutual Coupling Effect in the Protein-Water-Glycerol Mixture by Combining Neutron Scattering and Selective Deuteration.

Numerous studies have discussed the impact of cosolvents on the structure, dynamics, and stability of proteins in aqueous solutions. However, the dynamics of cosolvents in the protein-water-cosolvent ternary system is largely unexplored in experiments due to technical difficulty. Consequently, a comprehensive understanding of the interplay among proteins, water, and cosolvents is still lacking. Here, we employed selective deuteration and neutron scattering techniques to characterize the individual motions of each component in the protein/water/glycerol (GLY) mixture across various temperatures. The consistent dynamic onset temperatures and the correlation between the MSD of the protein and the viscosity of solvents revealed the mutual coupling effects among the three components. Furthermore, our experimental and simulation results showed that the hydrogen bond relaxation energy barrier in the ternary system is ∼43 kJ/mol, whereas in the protein-water binary system it is merely ∼35 kJ/mol. Therefore, we suggest that GLY can enhance hydrogen bond interactions in the ternary system through the mutual coupling effect, thereby serving as one of the protective mechanisms of protein preservation by GLY.

Mrs HYBRID MUTUAL COUPLING REDUCTION TECHNIQUES IN MULTIPLE INPUT AND MULTIPLE OUTPUT ANTENNA FOR X-BAND APPLICATIONS

In recent years, Multiple Input and Multiple Output antennas (MIMO) used for high-bandwidth communications where it's important to not have interference from microwave or RF systems. The MIMO antenna offers good matching with stable gain and desired radiation patterns but it suffers on mutual coupling effects. The spacing between antenna elements is less than half the wavelength, and then mutual coupling effects are more. This paper provides a review on different mutual coupling reduction techniques in MIMO antenna. In this letter, a hybrid mutual coupling reduction technique such as substrate integrated waveguide (SIW) and defected ground structure (DGS) in MIMO antennas for X-band applications. The developed MIMO antenna has dimensions as 25 x 36 mm over a FR4 1.6 mm substrate. The MIMO antenna has formed by combining two fractal-shaped structures. Here, the antenna element spacing is taken as minimum of 5.62mm. To reduce the mutual coupling effect and enhance gain, hybrid techniques are used. By adding 24 hollow cylindrical SIW is placed in between a MIMO element and six rectangular DGS slots placed at the bottom of the antenna for reducing the mutual coupling and enhance the gain. The proposed antenna operates at resonating frequencies of 10.04 GHz, 11.14 GHz, and 11.69 GHz for measurement. The mutual coupling or isolation loss was observed around &lt;-25 dB. The envelope correlation coefficient (ECC) and diversity gain (DG) of the proposed antenna are 0.0016 and &gt;9 dB, respectively. The gain observed for the proposed design is 5.2 dB. The Ansys high-frequency structure simulator (HFSS) tool is used for antenna simulation.

Corrections to “Effects of Mutual Coupling on LTE MIMO Capacity for Monopole Array: Comparing Reverberation Chamber Tests and Drive Tests”

Corrections to “Effects of Mutual Coupling on LTE MIMO Capacity for Monopole Array: Comparing Reverberation Chamber Tests and Drive Tests”

Mutual Coupling Effect on Spectral Efficiency of 5G Massive MIMO Millimeter Wave Antenna Array

Mutual Coupling Effect on Spectral Efficiency of 5G Massive MIMO Millimeter Wave Antenna Array

Research on intelligent control and sensor application strategy of motor based on RFID technology

Abstract People widely use permanent magnet brushless DC motors because of their simple structure, high operating efficiency, simple control, and easy maintenance. This paper constructs an EFID sensor network by merging EFID and sensor technologies and then designs the motor’s intelligent control system and strategy around it. In this paper, the SVR-PSO algorithm is used to localize the motor rotor, which nonlinear SVR trains to construct a nonlinear system of equations for calculating the position of the target tag, and then the PSO algorithm is used to seek the position coordinates of the target tag. The fuzzy PID is utilized to control the brushless DC motor, and the integral separation method is adopted to improve the control strategy. The SVR-PSO positioning algorithm and the improved fuzzy PID control strategy are applied and analyzed. For 12 tags to be measured, the positioning accuracy of SVR-PSO has improved by 56.8% compared to that of LANDMARC. Although SVR-PSO’s positioning algorithm is influenced by mutual coupling and multipath effects, the overall accuracy is still superior to that of LANDMARC. Based on the fuzzy PID controller optimized by the integral separation method, the motor rotational speed has a fast response, a small overshoot, and a small fluctuation of rotational speed, and can automatically regulate and restore stability under the situation of a sudden change of load. The motor speed response is fast, the overshoot is small, and the speed fluctuation is small, and the motor speed can be automatically adjusted and stabilized under the sudden load change, which has better dynamic and static performance than the traditional PID controller and fuzzy PID controller. The purpose of this paper is to provide a strategy reference for the use of RFID technology in the intelligent control of motors.

Performance analysis of the mutual coupling effect on Phased Array Feeds

Performance analysis of the mutual coupling effect on Phased Array Feeds