Coupling Reduction Research Articles

Mutual Coupling Effect and Reduction Method with Modified Electromagnetic Band Gap in UWB MIMO Antenna

In this paper, an effective technique for mutual coupling (MC) reduction between antenna elements of two multiple input multiple output (MIMO) microstrip patch antennas operating in the ultra-wide band (UWB) between 3.1 and 13.5 GHz is presented. The antenna array separation was kept at 44 mm for investigation, and the isolation was achieved through a modified electromagnetic band gap (MEBG) decoupling structure. The MEBG is embedded behind the radiating elements connected to the ground plane. HFSSv15 software was used to design and simulate the antenna. The effectiveness of the antenna and the MC reduction method was examined with and without the MEBG structure. The results revealed that the MC between the MIMO antenna elements was minimized when the MEBG structure was introduced. An MC of about −23 dB was obtained over the entire UWB frequency spectrum. This is more than a 10 dB improvement over the reference antenna (without the MEBG structure). Without limiting the effectiveness of the antenna when the MEBG structure was introduced, the results of the envelope correlation coefficient (ECC) gave the antenna a satisfactory diversity performance. The MEBG UWB MIMO antenna has an ECC less than 0.09 with a wide bandwidth. In addition, the total gain and the Voltage Standing Ware Ratio (VSWR) results were analyzed, which show that the performance of the antenna was not degraded while reducing the MC effect between the MIMO antenna elements.

Synthesis, characterization, catalytic reduction of Eosin B dye and C, N cross coupling reactions of sodiumalginate/V2O5 nanocomposite

BackgroundA low cost with high efficiency sodiumalginate (SA)/V2O5 nanocomposite catalyst was synthesized by complexation followed by reduction method. The V2O5 catalyst and SA was chemically linked with each other and hence restriction in diffusion of the catalyst into the reaction medium during the course of the reaction. The catalytic activity of SA/V2O5 bio-nano catalyst system was tested towards the C, N cross coupling reaction and reduction of EB dye. MethodsThe bio-polymer nanocomposite formation was confirmed by FT-IR spectroscopy, 1H-NMR spectroscopy, DSC (Tg) and TGA (Td) and HR-TEM (size) like analytical tools. The cross coupling reaction between rosebengal (RB) and nitrogen containing heterocyclic compounds like indole, benzimidazole, 2-methylimidazole were carried out. Same type of reaction was carried out with congored (CR), acidfuchsin (AF) and safranine O (SO) dyes. Further, the catalytic activity of SA/V2O5 nanocomposite catalyst was tested towards the reduction of Eosin blue (EB) dye. Significant findingsThe FTIR spectrum showed a peak at 615 cm−1 due to the V-O stretching. The 1H-NMR spectrum confirmed that the OH group of SA involved in the complex formation with V atom of V2O5. The Tg and Td of the SA/V2O5 bio-polymer nanocomposite system was higher than that of the neat polymer. The apparent rate constant (kapp) value was found to be higher in the presence of SA/V2O5 catalyst system. The C,N cross coupling reaction was successfully carried out with significant % yield in the presence of low cost and eco-friendly SA/V2O5 nano catalyst. The catalyst was stable up to several cycles of operations.

Mutual Coupling Reduction in CP MIMO Crossed-Dipole Antenna Array

In this letter, a circularly polarized (CP) 1×2 multiple-input–multiple-output (MIMO) crossed-dipole antenna array is investigated. The antenna element consists of a pair of orthogonal linear dipoles, which are connected by two quarter phase-delay lines, generating CP fields. It is found that within the operating CP band, both the excited and coupled crossed-dipole antennas are of circular operation and the mutual coupling is rather strong, but at higher frequency there exists a self-decoupled band (transmission stopband with low | <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> |) in which the excited antenna is of elliptical polarization while the coupled antenna is of linear polarization. In order to reduce the mutual coupling level in the operating band and make it applicable, a single metallic post is added in the middle of the MIMO array, shifting the self-decoupled band downwards to the desired CP band. As a result, the port isolation is enhanced by 13 dB and becomes higher than 20 dB within the entire CP bandwidth of 13.2%.

Compact circularly polarized 2 and 4 port multiple input multiple output antennas with bandstop filter isolation technique

Reduction of mutual coupling in the radiating elements of multiple input multiple output (MIMO) antenna is always an issue and a big challenge for antenna researchers. To address this issue of mutual coupling reduction, an effective method of decoupling has been proposed in this paper. Here, a bandstop filter based isolation technique has been introduced to limit the mutual coupling in each element of the MIMO antenna. A 2 port and a 4 port MIMO antenna have been designed with the proposed decoupling technique, and it is found that the decoupling technique successfully achieves isolation of more than 30 dB for both antennas. In addition to achieving high isolation, the designed MIMO antennas are also made circularly polarized to overcome poor mismatch, lower directive gain, and signal to noise problems in wireless communication. The antenna performance is observed in simulation and verified with measurements. Simulated and measured results show that the 2 port antenna exhibits a 10 dB impedance bandwidth of 5.26 % (2.78–2.93 GHz) and a 3 dB axial ratio bandwidth of 13.08 % (2.65–3.02 GHz), while those for the 4 port antenna are 2.46 % (2.41–2.47 GHz) and 13.10 % (2.36–2.69 GHz). The 2 port antenna supports a peak gain of 3.27 dBi with a maximum efficiency of 85.11 %, while the 4 port antenna successfully increases the gain to 6.49 dBi but decreases the maximum efficiency to 80.54 %. Both the MIMO antennas show excellent diversity performance in terms of envelope correlation coefficient (ECC), Directive Gain (DG), Total active reflection coefficient (TARC), channel capacity loss (CCL), and mean effective gain (MEG) ratio. Both the structures achieve ECC of less than 0.006, DG of more than 9.9 dB, TARC of less than −19.84071 dB, CCL of less than 0.00179 bits/s/Hz, and MEG of less than −0.00577 dB in measurements. The overall dimensions of 2 port and 4 port antennas are limited to 44×22×1.6mm3 and 44×52×1.6mm3, respectively. These characteristics of the proposed antennas make them suitable for use in wireless high-speed communications.

Mutual coupling compensation of linear antenna array using evolutionary optimization technique

SummaryThis paper presents an optimization‐based approach to compensate for the mutual coupling effect and to reduce the sidelobe level (SLL) of the normalized radiation pattern by optimizing the current excitation amplitude of the antenna array elements. Due to the mutual coupling effect, the SLL of the radiation pattern is increased, and thereby, the field pattern of the antenna array is severely degraded. This causes interference with other communication systems working at the same frequency. Toward the compensation of the mutual coupling effect and reduction of SLL, the Cat swarm optimization (CSO) algorithm is employed, and the excitation amplitudes of the antenna elements are optimized. In this regard, optimizing the cost function is defined by introducing the impedance factor (IF), calculated by using the self‐impedance and mutual impedance of the antenna elements. The proposed method for the synthesis of a mutually coupled linear antenna array is less expensive, simpler to use, and more effective. Array sets of 4, 6, 8, and 10 elements are considered for optimization.

Cardiolipin Alterations during Obesity: Exploring Therapeutic Opportunities

Cardiolipin is a specific phospholipid of the mitochondrial inner membrane that participates in many aspects of its organization and function, hence promoting proper mitochondrial ATP production. Here, we review recent data that have investigated alterations of cardiolipin in different tissues in the context of obesity and the related metabolic syndrome. Data relating perturbations of cardiolipin content or composition are accumulating and suggest their involvement in mitochondrial dysfunction in tissues from obese patients. Conversely, cardiolipin modulation is a promising field of investigation in a search for strategies for obesity management. Several ways to restore cardiolipin content, composition or integrity are emerging and may contribute to the improvement of mitochondrial function in tissues facing excessive fat storage. Inversely, reduction of mitochondrial efficiency in a controlled way may increase energy expenditure and help fight against obesity and in this perspective, several options aim at targeting cardiolipin to achieve a mild reduction of mitochondrial coupling. Far from being just a victim of the deleterious consequences of obesity, cardiolipin may ultimately prove to be a possible weapon to fight against obesity in the future.

Innovation Strategy for Green Development and Carbon Neutralization in Guizhou—An Overview

A carbon peak in 2030 and carbon neutrality in 2060 are major strategic development goals for China. Driven by the ambitious goal of achieving a carbon peak and carbon neutrality, the development of green innovation technology is an important method of achieving these aims. Speeding up energy transformation and tapping into the carbon sink capacity of the natural ecosystem are key to this process. The strategic path of green development deserves further discussion. This study takes Guizhou province as an example. Based on the actual situation of Guizhou province and the characteristics of karst areas, through the collection and collation of the existing literature, policies, and technologies and the analysis of typical cases, this paper summarizes and analyzes ecological restoration and negative carbon emissions in karst areas; water-energy-carbon coupling, energy saving, and emissions reduction technologies; industrial energy saving and emission-reduction technologies in karst areas; and CCUS technology for carbon dioxide capture, utilization, and storage. On this basis, the trend and orientation of green development in Guizhou are studied and judged, and countermeasures such as adhering to clean and efficient low-carbon utilization, strengthening the research on and development of carbon emission-reduction technology, and implementing carbon sink capacity buildings are put forward. Key core technology research and development innovation are recommended to establish a low-carbon science and technology innovation system. The efficient use of energy, the recycling of resources, negative emissions, and other strategies should be promoted. We also posit specific suggestions such as accelerating the transformation and application of green and low-carbon scientific and technological achievements.

Mutual coupling and RCS reduction of MIMO dielectric resonator antenna for S-band applications

This paper designs and analyses a two-port dielectric resonator-based multiple-input, multiple-output (MIMO) antenna. A tilted L-shaped aperture is used to excite the cylindrical-shaped ceramic. This type of feeding structure produces the circularly polarized (CP) waves and HEM11δ mode inside the ceramic. The proposed antenna shows two main features: (i) the polarization diversity concept reduces the isolation level by 15 dB; (ii) integration of frequency-selective surface (FSS) reduces the radar cross-section (RCS) value by an amount of 7.5 dBsm within the operating band. The fabricated structure confirms the working band of the proposed antenna from 2.8 to 3.2 GHz. 3-dB axial ratios is achieved between 2.8 and 3.05 GHz. The proposed antenna's good diversity parameter value and stable radiation characteristics make it applicable for S-band wireless applications

Investigation of isolation enhancement and tune‐ability in patch antenna arrays

AbstractThis paper reports the study of a tunable isolator based on a four‐strip resonant structure to reduce the mutual coupling between two patch antennas. Unlike other decoupling structures with a fixed center decoupling frequency, this design provides tunable mutual coupling reduction frequency response and adjustable mutual coupling level by integrating a varactor diode into the strip isolator. This study investigates the effect of the position and capacitance of the varactor diode on mutual coupling. In addition to tune‐ability, the tunable four‐strip resonator reduces the coupling level at all frequencies around 3.5 GHz by at least 6 dB to less than –28 dB without degrading the impedance bandwidth. Compared to the case with the four‐strip resonator structure but without the varactor diode, the isolation is further improved by 2 dB or more. The measured results are consistent with the simulation results.

Infrastructure Material Magnetization Impact Assessment of Wireless Power Transfer Pavement Based on Resonant Inductive Coupling

Wireless Power Transfer (WPT) is a promising technology applied in the intelligent transportation infrastructure. This technology can charge electric vehicles dynamically through resonant inductive coupling. The application of WPT is of significance to vehicle-road collaboration. This paper focused on the impact of pavement infrastructure material magnetization on resonant inductive coupling. Here, the experimental analysis was conducted with a Series-Series topological WPT system. Six kinds of pavement materials, including AC-5, AC-13, SMA-5, SMA-13, OGFC-13, and Portland Cement Concrete, were employed as the transfer medium in the shape of rutting plate specimens. The active power and efficiency were recorded by monitoring the voltages and currents on both primary and secondary sides. The experimental analysis revealed the pavement materials changed the active power and efficiency by inductance enhancement and coupling reduction in resonant inductive coupling whose formulae were modified by two influencing factors: the inductance enhancement factor and coupling reduction factor. The influencing factors were varied by pavement materials’ magnetization properties. The influencing factors are useful for adjusting the WPT system’s component parameters to offset the magnetization impact. Moreover, water immersing was considered an environmental impact in the experiments, showing a reduction in the active power and efficiency. The waterproof between pavement layers is also necessary.

A High-Performance Tactical-Grade Monolithic Horizontal Dual-Axis MEMS Gyroscope With Off-Plane Coupling Suppression Silicon Gratings

This articledemonstrates the developments toward a high-performance monolithic wheeled structure horizontal dual-axis [pitch ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X-</i> axis) and roll ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Y</i> -axis)] microelectromechanical system (MEMS) gyroscope based on off-plane coupling suppression silicon gratings. Gyroscopes have been fabricated with a silicon-on-glass fabrication process with vacuum sealed in metal packaging. The featured gyroscope operates in split mode with the bandwidths of two axes devices both of ∼70 Hz. By unitizing two individual active restraining control loops that adjust the quadrature amplitude via differentially biasing the silicon gratings in real time, the off-plane mechanical couplings of the two sense modes are significantly reduced by ∼95 and ∼30 times, which enables ∼25-fold and ∼56-fold improvements in the bias instability (BI) for a typical dual-axis device. Tactical-grade performances are achieved for both the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X-</i> axis and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Y-</i> axis gyroscopes with angle random walk of 0.02 deg/√h and 0.045 deg/√h along with in-run BI of 0.26 deg/h and 0.65 deg/h, respectively, without any temperature compensation. The current preliminary results show great potential to achieve navigation grade precision by employing the mode-matching technique in the future. The use of silicon gratings for out-of-plane coupling reduction also provides an effective way to build a high-performance planar monolithic chip inertial measurement unit.

Polarization Selective Partial Reflective Decoupling Layers for Mutual Coupling Reduction of Two Closely Spaced Dual-Polarized Antennas

In this communication, two polarization selective partial reflective decoupling layers (PRDLs) are utilized to mitigate at least two kinds of mutual couplings between two closely spaced dual-polarized dipole antennas. The PRDL is a large-scale model of an actual dielectric board, obtained by arranging a large number of identical conducting obstacles in a regular two-dimensional pattern. The two PRDLs are designed at proper distances from the antenna aperture with well-engineered dielectric constants for two preset polarizations. Each layer is selective to only one polarization by appropriately designing the dimension of the unit cells. Consequently, the two dominant couplings between the two dual-polarized antennas are reduced significantly. The measured isolation between all ports of the two antennas are increased to more than 21 dB, while their reflection coefficients can still maintain in satisfactory status. The radiation patterns, total efficiencies, and envelop correlation coefficients of the proposed antenna, as well as its counterpart without any decoupling measures, are also obtained through measurement, showing significant and reasonable improvements, which further indicates that it has great potential to be extended and applied to 5G MIMO arrays in both base stations and wireless routers.

A Cancelling-Blocking structure for decoupling of microstrip antenna array

In this work, a cancelling-blocking structure (CBS) for decoupling of microstrip antennas was proposed, which can reduce the coupling between arbitrary elements of a one-dimensional E-plane antenna. Results demonstrate the optimized active VSWR and improved radiation efficiency. The cancelling-type decoupling structure consists of a plurality of electrically small metal sheet arrays printed on the dielectric above the antenna. The blocking-type decoupling structure means that each element uses independent dielectric and ground plane to cut off the coupling current propagation path. Firstly, the decoupling principle of the cancelling-type decoupling structure was deduced, and the decoupling conditions were obtained. Then, the mechanism of the surface wave in the antenna array was qualitatively analyzed, and the applicable conditions of the blocking-type decoupling structure were deduced. To verify the proposed structure, a 1×8 E-plane antenna with the designed CBS was modeled. Simulation results manifested that a mutual coupling reduction of more than 10 dB in 1.2-1.3 GHz was achieved, and the active VSWR was below 2.0 over the range of ±60° scan angle.

MIMO antenna array with the capability of dual polarization reconfiguration for 5G mm-wave communication

This communication presents a polarization reconfigurable antenna array (PRAA) with Multi-input Multi-output (MIMO) formation for 5th generation (5G) millimeter wave (mm-Wave) communications. At first a single corner curtailed diagonal slotted cylindrical patch is printed on Roger RT Duriod 5880 and the overall size of the single antenna is 12 × 12 × 0.787 mm3. The circular polarization (CP) is realized by adding the diagonal slot in the circular patch. The antenna design is extended into two elements antenna array which occupies 20 × 20 × 0.787 mm3 footprint. The collection is formed using a T-shaped power divider/combiner. Pin-diodes are integrated with the patches to switch the polarization state between LP (Linear polarization) and CP radiation. The edge-to-edge distance between antenna elements is 6 mm. The design covers the 25.2–29.4 GHz band, and the maximum peak gain is 11.5 dBi. Moreover, a two-port (2 × 2) MIMO design is formed to increase the channel capacity. To isolate the ports, a sin-like slot is engraved in the ground, defected ground structure (DGS) technique of mutual coupling reduction; it can easily be implemented and increases the design efficiency. The port isolation is well above 30 dB for the entire operating band. Moreover, the Mean Effective Gain (MEG), Diversity Gain (DG), and Envelope Correlation Coefficient (ECC) are investigated, which are key performance metrics of MIMO. A prototype of the realized MIMO antenna system is fabricated, and the simulated outcomes carried out by Computer Simulation Technology (CST) tools are validated by experimental findings.

Coupled CO2 reduction and Alcohol Oxidation for Fuel Synthesis and CO2 Utilization

Electro-conversion CO2 to fuels like formic acid, methanol, and ethanol is an attractive method to recycle CO2 and close the carbon cycle associated with these fuels, which could benefit the environment, national energy security Many CO2 electrolyzers oxidize water or hydroxyl ions as a counter reaction which releases oxygen. However, this can lead to a large cell potential due to oxygen’s large, positive reduction potential. Further, oxygen is a relatively low-value product. These systems also use an ion exchange membrane to prevent crossover of CO2 reduction products to the anode while conducting ions between the electrodes.Instead of oxygen evolution, the partial oxidation of alcohols could serve as the anodic counter reaction to synthesize oxygenated fuel additives. Partial alcohol oxidation could be coupled with CO2 reduction which could regenerate the alcohol. Coupling the anodic and cathodic reactions in this way could preclude the need for an ion exchange membrane, and lower required energy input by decreasing the thermodynamic cell voltage. Our system is also capable of high-pressure operation, which could allow higher concentrations of CO2 in the electrolyte. This study examines the use of alcohol/water mixtures as a working fluid for a CO2 electrolyzer, and the effect of pressure and catalyst composition on the current density and product selectivity. Linear sweep voltammetry and chronoamperometry will be used to evaluate the current densities and cell voltages for different catalysts at pressures up to 90 bar. Gas and liquid products will be analyzed following chronoamperometry studies to determine the faradaic efficiencies. Noble and transition metal catalysts will be used at the cathode and anode based on their purported ability to drive CO2 reduction to alcohol and partial oxidation of alcohols.

Charge Delocalization and Vibronic Couplings in Quadrupolar Squaraine Dyes.

Squaraines are prototypical quadrupolar charge-transfer chromophores that have recently attracted much attention as building blocks for solution-processed photovoltaics, fluorescent probes with large two-photon absorption cross sections, and aggregates with large circular dichroism. Their optical properties are often rationalized in terms of phenomenological essential state models, considering the coupling of two zwitterionic excited states to a neutral ground state. As a result, optical transitions to the lowest S1 excited state are one-photon allowed, whereas the next higher S2 state can only be accessed by two-photon transitions. A further implication of these models is a substantial reduction of vibronic coupling to the ubiquitous high-frequency vinyl-stretching modes of organic materials. Here, we combine time-resolved vibrational spectroscopy, two-dimensional electronic spectroscopy, and quantum-chemical simulations to test and rationalize these predictions for nonaggregated molecules. We find small Huang-Rhys factors below 0.01 for the high-frequency, 1500 cm-1 modes in particular, as well as a noticeable reduction for those of lower frequency modes in general for the electronic S0 → S1 transition. The two-photon allowed state S2 is well separated energetically from S1 and has weak vibronic signatures as well. Thus, the resulting pronounced concentration of the oscillator strength in a narrow region relevant to the lowest electronic transition makes squaraines and their aggregates exceptionally interesting for strong and ultrastrong coupling of excitons to localized light modes in external resonators with chiral properties that can largely be controlled by the molecular architecture.

Miniaturized Parasitic Loaded High-Isolation MIMO Antenna for 5G Applications.

In this paper, a multiple-input–multiple-output (MIMO) antenna is reported for 5G frequency range-2 (FR-2), 28 GHz bands. The MIMO antenna is developed in multiple iterations, including single-element design, cross-polarization reduction, and mutual coupling reduction. Initially, a single-element coplanar edge feed rectangular patch antenna is designed and the E-plane cross-polarization is reduced by −13 dB by trimming the forward corners of the patch. The ground plane is truncated to improve the −3 dB half-power-beamwidth (HPBW). A multi-wavelength spiral inspired parasitic surrounding the single element antenna is loaded, and performance analysis is performed. This parasitic element is used for self-field cancelation for the MIMO configuration. Two MIMO configurations, one with linear and the second with inverted elements, are developed and investigated. The first configuration is found to have better isolation of less than −25 dB compared to the −20 dB of the second configuration. Similarly, the gain of 4.8 dBi, the bandwidth of 3 GHz, envelope correlation coefficient (ECC) of 0.01, and diversity gain (DG) of 9.99 dB are superior to the second configuration. To validate the work, one of two MIMO configurations is fabricated and good agreement is found between simulation and measurement results.

Single/Dual/Triple Broadband Metasurface Based Polarisation Converter with High Angular Stability for Terahertz Applications.

This paper presents design and characterisation of a new compact metasurface based linear polarisation converter for terahertz applications. The metasurface unit cell with periodicity of 0.292 consists of an asymmetrically oriented planar double semicircular goblet-shaped resonators. It is printed on a polydimethylsiloxane (PDMS) dielectric substrate backed by a gold layer that acts as a ground plane. This metasurface structure exhibits a broadband cross-polarisation conversion in the frequency range of 0.72–0.99 THz with a polarisation conversion ratio (PCR) > 95% and angular stability > for both TE and TM modes. However, the PCR for the single band is >99% at resonant frequencies of 0.755 and 0.94 THz, while the optimised design shows 100% PCR over a BW of 95 GHz. Furthermore, slight modification and optimisation of the broadband design results in quad-ring and slotted DSGRs that produce dual and triple broadband polarisation conversion, respectively. The quad-ring DSGR performs polarisation conversion for frequency range of 0.70–1.08 and 1.61–1.76 THz while the slotted DSGR shows the triple broadband cross-conversion for frequency range of 0.67–0.85, 1.04–1.11, and 1.62–1.76 THz with PCR > 95%. This design is simple, easy to modify to implement single and multi broadband polarisation conversion with high PCR at terahertz regime. In addition to that, it is easy to fabricate and integrate with other components like multiple-input multiple-output terahertz antennas for mutual coupling reduction.

TNF-α Plus IL-1β Induces Opposite Regulation of Cx43 Hemichannels and Gap Junctions in Mesangial Cells through a RhoA/ROCK-Dependent Pathway.

Connexin 43 (Cx43) is expressed in kidney tissue where it forms hemichannels and gap junction channels. However, the possible functional relationship between these membrane channels and their role in damaged renal cells remains unknown. Here, analysis of ethidium uptake and thiobarbituric acid reactive species revealed that treatment with TNF-α plus IL-1β increases Cx43 hemichannel activity and oxidative stress in MES-13 cells (a cell line derived from mesangial cells), and in primary mesangial cells. The latter was also accompanied by a reduction in gap junctional communication, whereas Western blotting assays showed a progressive increase in phosphorylated MYPT (a target of RhoA/ROCK) and Cx43 upon TNF-α/IL-1β treatment. Additionally, inhibition of RhoA/ROCK strongly antagonized the TNF-α/IL-1β-induced activation of Cx43 hemichannels and reduction in gap junctional coupling. We propose that activation of Cx43 hemichannels and inhibition of cell–cell coupling during pro-inflammatory conditions could contribute to oxidative stress and damage of mesangial cells via the RhoA/ROCK pathway.

Polarization Converter Surface Integrated MIMO Antenna for Simultaneous Reduction of RCS and Mutual Coupling

This letter provides an effective solution to deal with the radar cross section (RCS) and mutual coupling of the multiple-input–multiple-output (MIMO) antenna simultaneously. A wideband reflective type polarization converter (PC) is designed and its strategic placement in between the antenna elements of the two-element MIMO antenna has been conceived to mitigate these two issues concurrently. The antenna elements of the proposed MIMO antenna are placed at a proximal distance of 0.088 λ from each other. The proposed MIMO architecture ensures a maximum coupling reduction of 46 dB compared to the conventional MIMO across 4.4–8 GHz. The PC surface reduces the reflection of copolarized waves and enhances cross-polarized reflection. A supercell formed by a unit cell of PC and its 90° rotated counterpart causes phase cancellation of cross- polarized reflected waves, which contributes to wideband RCS reduction by a maximum value of 7 dB. The alignment of PC cells in a column between the adjacent antenna elements causes a reduction in the mutual coupling due to introduction of an extra coupling path and cross-polarization conversion. A good agreement between the simulated and measured results validates this concept of the proposed MIMO design with low RCS and mutual coupling.