To address the significant degradation of Space-Time Adaptive Processing(STAP)performance when the array elements have mutual coupling and gain/phase errors,a STAP algorithm with adaptive calibration for the above two...To address the significant degradation of Space-Time Adaptive Processing(STAP)performance when the array elements have mutual coupling and gain/phase errors,a STAP algorithm with adaptive calibration for the above two array errors is proposed in this article.First,based on a defined error matrix that simultaneously considers both array mutual coupling and gain/phase errors,a STAP signal model including these errors is given.Then,utilizing the defined signal model,it is demonstrated that the estimation of the defined error matrix can be formulized as a standard convex optimization problem with the low-rank structure of the clutter covariance matrix and the subspace projection theory.Once the defined error matrix is estimated by solving the convex optimization problem,it is illustrated that a STAP method with adaptive calibration of the mutual coupling and gain/phase errors is coined.Analyses also show that the proposed adaptive calibration algorithm only needs one training sample to construct the adaptive weight vector.Therefore,it can achieve a good detection performance even with severe non-homogeneous clutter environments.Finally,the simulation experiments verify the effectiveness of the proposed algorithm and the correctness of the analytical results.展开更多
A phased array feed(PAF)is a type of receiving array that places phased array antennas on the focal plane of a radio telescope to expand its field of view and improve observation efficiency.Owing to the mutual couplin...A phased array feed(PAF)is a type of receiving array that places phased array antennas on the focal plane of a radio telescope to expand its field of view and improve observation efficiency.Owing to the mutual coupling effect between elements caused by a tightly arranged feed array,which changes the performance of a PAF,this paper presents a 7×7 rectangular feed array model for a 25 m reflector telescope.By adjusting the element spacings,the performance of a PAF with different spacings is comprehensively analyzed with respect to the mutual coupling effect via performance statistics and comparison.This research aims to provide a reference for the preliminary design of a related PAF.展开更多
The fifth generation (5G) wireless communication requires the massive multiple input multiple output (MIMO) technique. The massive MIMO antenna array of the millimeter wave (mm-wave) is recognized as a key enabler bec...The fifth generation (5G) wireless communication requires the massive multiple input multiple output (MIMO) technique. The massive MIMO antenna array of the millimeter wave (mm-wave) is recognized as a key enabler because of its high spectral efficiency. The higher the frequencies of the RF signal, the lower the distance it travels in free space caused by path loss, and it is more easily absorbed by obstacles, which are needed for high-gain transmitters. The advantage of the physical properties of higher New Radio (NR) frequencies is that 5G can utilize more spectrum, more antennas, and higher-order modulation schemes. The massive antennas and radio frequency chains improve the implementation of the cost of 5G wireless communication systems and result in an intense mutual coupling effect among antennas because of the limited space for deploying antennas. The upper bound of the effective capacity is derived for 5G multimedia massive MIMO communication systems. Two antennas that receive diversity gain models, the mutual coupling matrix, and the spacing antenna distance are built and analyzed. The impacts and affections of the antenna spacing the number of antennas, the quality-of-service (QoS) statistical exponent, and the number of independent incident directions on the upper effective capacity of 5G multimedia massive MIMO communication systems are analyzed. It is shown that for MIMO systems with compact transmit antenna arrays, the mutual coupling seriously degrades system capacity to mitigate the capacity degradation. In case of improvement in the mutual coupling by 99%, the system performance is kept stationary and enhances system capacity. However, the improvement of the mutual coupling is still about 87.5% today, which means the mutual coupling should be considered in 5G massive MIMO networks.展开更多
We propose a method for estimating the mutual coupling coefficient among antennas in this paper which is based on the principle of signal subspace and the simulated annealing （SA） algorithm. The computer simulation ...We propose a method for estimating the mutual coupling coefficient among antennas in this paper which is based on the principle of signal subspace and the simulated annealing （SA） algorithm. The computer simulation has been conducted to illustrate the＇ excellent performance of this method and to demonstrate that it is statistically efficient. The benefit of this new method is that calibration signals and unknown signals can be received simultaneously, during the course of calibration.展开更多
The effect of gain-phase perturbations and mutual coupling significantly degrades the performance of digital array radar (DAR). This paper investigates array calibration problems in the scenario where the true locatio...The effect of gain-phase perturbations and mutual coupling significantly degrades the performance of digital array radar (DAR). This paper investigates array calibration problems in the scenario where the true locations of auxiliary sources deviate from nominal values but the angle intervals are known. A practical algorithm is proposed to jointly calibrate gain-phase errors and mutual coupling errors. Firstly, a simplified model of the distortion matrix is developed based on its special structure in uniform linear array (ULA). Then the model is employed to derive the precise locations of the auxiliary sources by one-dimension search. Finally, the least-squares estimation of the distortion matrix is obtained. The algorithm has the potential of achieving considerable improvement in calibration accuracy due to the reduction of unknown parameters. In addition, the algorithm is feasible for practical applications, since it requires only one auxiliary source with the help of rotation platforms. Simulation results demonstrate the validity, robustness and high performance of the proposed algorithm. Experiments were carried out using an S-band DAR test-bed. The results of measured data show that the proposed algorithm is practical and effective in application. (C) 2016 Production and hosting by Elsevier Ltd. on behalf of Chinese Society of Aeronautics and Astronautics.展开更多
A decoupling-estimation signal parameters via rotarional invariance technique（ESPRIT） method is presented for multi-target localization with unknown mutual coupling in bistatic multiple-input multiple-output（MIMO）...A decoupling-estimation signal parameters via rotarional invariance technique（ESPRIT） method is presented for multi-target localization with unknown mutual coupling in bistatic multiple-input multiple-output（MIMO） radar.Two steps are carried out in this method.The decoupling operation between angle and mutual coupling estimates is realized by choosing the auxiliary elements on both sides of the transmit and receive uniform linear arrays（ULAs）.Then the ESPRIT method is resilient against the unknown mutual coupling matrix（MCM） and can be directly utilized to estimate the direction of departure（DOD） and the direction of arrival（DOA）.Moreover,the mutual coupling coefficient is estimated by finding the solution of the linear constrained optimization problem.The proposed method allows an efficient DOD and DOA estimates with automatic pairing.Simulation results are presented to verify the effectiveness of the proposed method.展开更多
Anovel compact E shape High Impedance Surface(HIS) Electromagnetic Band-Gap(EBG) comprising Amended Minkowski Fractal Boundary(AMFB),Added Metal Strips(AMS),and metal plated via printed on a Rogers TMM 10i substrate i...Anovel compact E shape High Impedance Surface(HIS) Electromagnetic Band-Gap(EBG) comprising Amended Minkowski Fractal Boundary(AMFB),Added Metal Strips(AMS),and metal plated via printed on a Rogers TMM 10i substrate is presented.The first order AMFB and ABS are introduced for equivalent capacitance enhancement and miniaturization with effective space-filling characteristics.The dimension of lattice size is only The proposed structure exhibits a most compact characteristic about 35% size reduction as compared with conven-tional mushroom-like HIS-EBG,and better surface-wave decoupling of around 9 dB at the operating frequency band.Details of design parameters which affect the whole performance of certain band-gap are intensively investigated.A constructed prototype is potential candidate for antenna system per-formance enhancement.展开更多
A novel Direction-Of-Arrival (DOA) estimation method is proposed in the presence of mutual coupling using the joint sparse recovery. In the proposed method, the eigenvector corresponding to the maximum eigenvalue of c...A novel Direction-Of-Arrival (DOA) estimation method is proposed in the presence of mutual coupling using the joint sparse recovery. In the proposed method, the eigenvector corresponding to the maximum eigenvalue of covariance matrix of array measurement is viewed as the signal to be represented. By exploiting the geometrical property in steering vectors and the symmetric Toeplitz structure of Mutual Coupling Matrix (MCM), the redundant dictionaries containing the DOA information are constructed. Consequently, the optimization model based on joint sparse recovery is built and then is solved through Second Order Cone Program (SOCP) and Interior Point Method (IPM). The DOA estimates are gotten according to the positions of nonzeros elements. At last, computer simulations demonstrate the excellent performance of the proposed method.展开更多
A new and exact calculation method for the mutual impedance matrix of receiving arrays is proposed. The mutual impedance matrix is derived from electromagnetic boundary conditions and can be used to relate the couplin...A new and exact calculation method for the mutual impedance matrix of receiving arrays is proposed. The mutual impedance matrix is derived from electromagnetic boundary conditions and can be used to relate the coupling free open-circuit voltages, instead of the conventional ones, to the measured voltages. A remarkable improvement on compensation for the coupling effects is shown in the direction finding applications, while a simple relationship between measured terminal voltages and the coupling free voltages is remained.展开更多
In this paper, a novel algorithm is presented for direction of arrival（DOA） estimation and array self-calibration in the presence of unknown mutual coupling. In order to highlight the relationship between the array ...In this paper, a novel algorithm is presented for direction of arrival（DOA） estimation and array self-calibration in the presence of unknown mutual coupling. In order to highlight the relationship between the array output and mutual coupling coefficients, we present a novel model of the array output with the unknown mutual coupling coefficients. Based on this model, we use the space alternating generalized expectation-maximization（SAGE） algorithm to jointly estimate the DOA parameters and the mutual coupling coefficients. Unlike many existing counterparts, our method requires neither calibration sources nor initial calibration information. At the same time,our proposed method inherits the characteristics of good convergence and high estimation precision of the SAGE algorithm. By numerical experiments we demonstrate that our proposed method outperforms the existing method for DOA estimation and mutual coupling calibration.展开更多
A novel compact Swastika shaped patch antenna is designed in the present work,which can be used for Multiple Input Multiple Output(MIMO) systems.The proposed two element MIMO system resonates at a triband of 3.3 GHz,5...A novel compact Swastika shaped patch antenna is designed in the present work,which can be used for Multiple Input Multiple Output(MIMO) systems.The proposed two element MIMO system resonates at a triband of 3.3 GHz,5.8 GHz,and 7.1 GHz with an improved impedance bandwidth of 37% and a reduced mutual coupling of-33 dB.These results are better compared to a normal E shaped patch antenna designed with same size and thickness,achieved without using any additional decoupling methods.A 2×2 MIMO system employing the Swastika shaped patch antennas is analyzed using computational electromagnetic ray tracing software for an indoor environment.The results show an improvement in the capacity compared to a 2×2 MIMO system developed with dipole antennas.The proposed antenna is a good choice for MIMO systems operating for several Ultra WideBand(UWB) applications.展开更多
A mutual coupling suppression method is proposed for microstrip antenna array by cutting four small semi-circle annular apertures on the metal plate. The structure of antenna array is composed of 2 × 2 four eleme...A mutual coupling suppression method is proposed for microstrip antenna array by cutting four small semi-circle annular apertures on the metal plate. The structure of antenna array is composed of 2 × 2 four elements. The antenna consists of double layer dielectric, and it realizes circular polarization characteristics by cutting rectangular slot on circular patch in the direction of 45°, by using aperture coupling feeding and reverse feeding principle. There is 90＊ phase difference between adjacent antenna elements. Thus, it cuts off the coupling current field between the elements, suppresses the surface wave and reduces the mutual coupling by cutting four semi-circle annular apertures symmetrically on the metal plate. The simulation results show that after cutting four semi-circle annular apertures, the antenna array coupling coefficients decrease significantly, and the side and back lobe levels are suppressed effectively with the gain of antenna improved. So the proposed method is effective to suppress microstrip antenna array mutual coupling.展开更多
A unified mutual coupling model for multiple antenna communication systems based on moment methods is proposed. This model combines antenna coupling and RF front-end circuit coupling, thus providing a more accurate an...A unified mutual coupling model for multiple antenna communication systems based on moment methods is proposed. This model combines antenna coupling and RF front-end circuit coupling, thus providing a more accurate and complete analysis of the mutual coupling effect on multiple antenna systems.展开更多
The sensor array calibration methods tailored to uniform rectangular array(URA)in the presence of mutual coupling and sensor gain-and-phase errors were addressed.First,the mutual coupling model of the URA was studied,...The sensor array calibration methods tailored to uniform rectangular array(URA)in the presence of mutual coupling and sensor gain-and-phase errors were addressed.First,the mutual coupling model of the URA was studied,and then a set of steering vectors corresponding to distinct locations were numerically computed with the help of several time-disjoint auxiliary sources with known directions.Then,the optimization modeling with respect to the array error matrix(defined by the product of mutual coupling matrix and sensor gain-and-phase errors matrix)was constructed.Two preferable algorithms(called algorithm I and algorithm II)were developed to minimize the cost function.In algorithm I,the array error matrix was regarded as a whole parameter to be estimated,and the exact solution was available.Compared to some existing algorithms with the similar computation framework,algorithm I can make full use of the potentially linear characteristics of URA's error matrix,thus,the calibration precision was obviously enhanced.In algorithm II,the array error matrix was decomposed into two matrix parameters to be optimized.Compared to algorithm I,it can further decrease the number of unknowns and,thereby,yield better estimation accuracy.However,algorithm II was incapable of producing the closed-form solution and the iteration operation was unavoidable.Simulation results validate the excellent performances of the two novel algorithms compared to some existing calibration algorithms.展开更多
Based on the integral equation formulations and the moment method, a novel closed form solution for analyzing the mutual coupling effect between the cylindrical comformal rectangular microstrip patch antennas is pres...Based on the integral equation formulations and the moment method, a novel closed form solution for analyzing the mutual coupling effect between the cylindrical comformal rectangular microstrip patch antennas is presented. By using this algorithm, the elements of the impedance matrix and exciting vector are cast into closed forms, thus the computational efficiency is improved dramatically. Numerical results are presented to verify the validity and reliability of the algorithm.展开更多
A4-port multiple-input multiple-output(MIMO)antenna exhibiting lowmutual coupling andUWBperformance is developed.The octagonal-shaped four-antenna elements are connected with a 50microstrip feed line that is arranged...A4-port multiple-input multiple-output(MIMO)antenna exhibiting lowmutual coupling andUWBperformance is developed.The octagonal-shaped four-antenna elements are connected with a 50microstrip feed line that is arranged rotationally to achieve the orthogonal polarization for improving the MIMO system performance.The antenna has a wideband impedance bandwidth of 7.5GHz with S11<−10 dB from(103.44%)3.5–11GHz and inter-element isolation higher than 20 dB.Antenna validation is carried out by verifying the simulated and measured results after fabricating the antenna.The results in the form of omnidirectional radiation patterns,peak gain(≥4 dBi),and Envelope Correlation Coefficient(ECC)(≤0.01)are extracted to validate the suggested antenna performance.Aswell,time-domain analysis was investigated to demonstrate the operation of the suggested antenna in wideband applications.Finally,the simulated and experimental outcomes have almost similar tendenciesmaking the antenna suitable for its use in UWBMIMOapplications.展开更多
This work provides the design and analysis of a single layer,linearly polarized millimeter wave reflectarray antenna with mutual coupling optimization.Detailed analysis was carried out at 26GHz design frequency using ...This work provides the design and analysis of a single layer,linearly polarized millimeter wave reflectarray antenna with mutual coupling optimization.Detailed analysis was carried out at 26GHz design frequency using the simulations of the reflectarray unit cells as well as the periodic reflectarray antenna.The simulated results were verified by the scattering parameter and far-fieldmeasurements of the unit cell and periodic arrays,respectively.Aclose agreement between the simulated and measured results was observed in all the cases.Apart from the unit cells and reflectarray,the waveguide and horn antenna were also fabricated to be used in the measurements.The measured scattering parameter results of the proposed circular ring unit cells provided a maximum reflection loss of 2.8 dB with phase errors below 10°.On the other hand,the measured far-field results of the 20×20 reflectarray antenna provided a maximum gain of 26.45 dB with a maximum 3 dB beam width of 12°and 1 dB gain drop bandwidth of 13.1%.The performance demonstrated by the proposed reflectarray antenna makes it a potential candidate to be used in modern-day applications such as 5th Generation(5G)and 6th Generation(6G)communication systems.展开更多
Using the Method of Moments(MoM) and the spectral method, the effect of mutual coupling on the performance of adaptive arrays is compensated. First, the MoM is used to compute the behavior of the array, where the accu...Using the Method of Moments(MoM) and the spectral method, the effect of mutual coupling on the performance of adaptive arrays is compensated. First, the MoM is used to compute the behavior of the array, where the accurate analytical model and odd numbers of piecewise sinusoids are applied. Then the covariance matrix with mutual coupling being taken into account is analyzed, and the expression for the weight of the Least Mean Square(LMS) algorithm with mutual coupling being compensated is given. Finally, the method given in this letter is tested on an example.展开更多
An effective method is introduced to compensate the effects of mutual coupling for the Estimation of Signal Parameter via Rotational Invariance Techniques (ESPRIT) direction finding algorithm in application of signal ...An effective method is introduced to compensate the effects of mutual coupling for the Estimation of Signal Parameter via Rotational Invariance Techniques (ESPRIT) direction finding algorithm in application of signal snapshot array processing.Changing the covariance matrix into a Teoplitz matrix can achieve high resolution in the Direction Of Arrive (DOA) estimation.How the mutual coupling affects the array antennas has been discussed and a new definition of mutual im- pedance has been used to characterize the mutual coupling effects between the array elements.Based on the new mutual impedance matrix,a practical method is presented to eliminate the effects of mutual coupling for ESPRIT in the single snapshot data processing.The simulation results show that, this new method not only properly reduces the effects of mutual coupling,but also maintains its steady performance even for weak signals.展开更多
The number of wireless electronic gadgets used in mobile communication, vehicle collision avoidance system, compact radars, etc. is extremely increasing at a rapid rate. Thus, the characteristics of the antennas invol...The number of wireless electronic gadgets used in mobile communication, vehicle collision avoidance system, compact radars, etc. is extremely increasing at a rapid rate. Thus, the characteristics of the antennas involved in these gadgets are to be designed very stringently so as to avoid interferences & coupling and to improve compatibility, susceptibility, etc. Compact smart antenna with improved performance is highly essential to meet this challenging scenario. Mutual coupling between various elements of an array is one of the main factors which can be considered for improvement of performance of the antenna. Influence of mutual coupling on performance of the antenna is considered in this paper and various techniques to minimize this effect are presented. Effect of mutual coupling on radiation characteristics of the antenna can be compensated employing various methods like Conventional Mutual Impedance (CMI), Receiving Mutual Impedance (RMI). Analysis is presented as comparison between the two methods for different number of elements in the array. Analysis is also presented for different geometries of the array like circular and elliptical for improved performance. The results show performance improvement in the proposed array for parameters like SNR and Speed of convergence.展开更多
基金co-supported by the National Natural Science Foundation of China(No.12374431)。
文摘To address the significant degradation of Space-Time Adaptive Processing(STAP)performance when the array elements have mutual coupling and gain/phase errors,a STAP algorithm with adaptive calibration for the above two array errors is proposed in this article.First,based on a defined error matrix that simultaneously considers both array mutual coupling and gain/phase errors,a STAP signal model including these errors is given.Then,utilizing the defined signal model,it is demonstrated that the estimation of the defined error matrix can be formulized as a standard convex optimization problem with the low-rank structure of the clutter covariance matrix and the subspace projection theory.Once the defined error matrix is estimated by solving the convex optimization problem,it is illustrated that a STAP method with adaptive calibration of the mutual coupling and gain/phase errors is coined.Analyses also show that the proposed adaptive calibration algorithm only needs one training sample to construct the adaptive weight vector.Therefore,it can achieve a good detection performance even with severe non-homogeneous clutter environments.Finally,the simulation experiments verify the effectiveness of the proposed algorithm and the correctness of the analytical results.
基金This work was supported by the Chinese Academy of Sciences"Light of West China"Program(2020-XBQNXZ-018)the National Natural Science Foundation of China(11973078)the Natural Science Foundation of Xinjiang Uygur Autonomous Region(2022D01A358)。
文摘A phased array feed(PAF)is a type of receiving array that places phased array antennas on the focal plane of a radio telescope to expand its field of view and improve observation efficiency.Owing to the mutual coupling effect between elements caused by a tightly arranged feed array,which changes the performance of a PAF,this paper presents a 7×7 rectangular feed array model for a 25 m reflector telescope.By adjusting the element spacings,the performance of a PAF with different spacings is comprehensively analyzed with respect to the mutual coupling effect via performance statistics and comparison.This research aims to provide a reference for the preliminary design of a related PAF.
文摘The fifth generation (5G) wireless communication requires the massive multiple input multiple output (MIMO) technique. The massive MIMO antenna array of the millimeter wave (mm-wave) is recognized as a key enabler because of its high spectral efficiency. The higher the frequencies of the RF signal, the lower the distance it travels in free space caused by path loss, and it is more easily absorbed by obstacles, which are needed for high-gain transmitters. The advantage of the physical properties of higher New Radio (NR) frequencies is that 5G can utilize more spectrum, more antennas, and higher-order modulation schemes. The massive antennas and radio frequency chains improve the implementation of the cost of 5G wireless communication systems and result in an intense mutual coupling effect among antennas because of the limited space for deploying antennas. The upper bound of the effective capacity is derived for 5G multimedia massive MIMO communication systems. Two antennas that receive diversity gain models, the mutual coupling matrix, and the spacing antenna distance are built and analyzed. The impacts and affections of the antenna spacing the number of antennas, the quality-of-service (QoS) statistical exponent, and the number of independent incident directions on the upper effective capacity of 5G multimedia massive MIMO communication systems are analyzed. It is shown that for MIMO systems with compact transmit antenna arrays, the mutual coupling seriously degrades system capacity to mitigate the capacity degradation. In case of improvement in the mutual coupling by 99%, the system performance is kept stationary and enhances system capacity. However, the improvement of the mutual coupling is still about 87.5% today, which means the mutual coupling should be considered in 5G massive MIMO networks.
基金Supported by the 863 High Technology Project ofChina (2001AA631050)
文摘We propose a method for estimating the mutual coupling coefficient among antennas in this paper which is based on the principle of signal subspace and the simulated annealing （SA） algorithm. The computer simulation has been conducted to illustrate the＇ excellent performance of this method and to demonstrate that it is statistically efficient. The benefit of this new method is that calibration signals and unknown signals can be received simultaneously, during the course of calibration.
基金supported by the National Natural Science Foundation of China (No. 61571449)
文摘The effect of gain-phase perturbations and mutual coupling significantly degrades the performance of digital array radar (DAR). This paper investigates array calibration problems in the scenario where the true locations of auxiliary sources deviate from nominal values but the angle intervals are known. A practical algorithm is proposed to jointly calibrate gain-phase errors and mutual coupling errors. Firstly, a simplified model of the distortion matrix is developed based on its special structure in uniform linear array (ULA). Then the model is employed to derive the precise locations of the auxiliary sources by one-dimension search. Finally, the least-squares estimation of the distortion matrix is obtained. The algorithm has the potential of achieving considerable improvement in calibration accuracy due to the reduction of unknown parameters. In addition, the algorithm is feasible for practical applications, since it requires only one auxiliary source with the help of rotation platforms. Simulation results demonstrate the validity, robustness and high performance of the proposed algorithm. Experiments were carried out using an S-band DAR test-bed. The results of measured data show that the proposed algorithm is practical and effective in application. (C) 2016 Production and hosting by Elsevier Ltd. on behalf of Chinese Society of Aeronautics and Astronautics.
基金supported by the National Natural Science Foundation of China (60702015)
文摘A decoupling-estimation signal parameters via rotarional invariance technique（ESPRIT） method is presented for multi-target localization with unknown mutual coupling in bistatic multiple-input multiple-output（MIMO） radar.Two steps are carried out in this method.The decoupling operation between angle and mutual coupling estimates is realized by choosing the auxiliary elements on both sides of the transmit and receive uniform linear arrays（ULAs）.Then the ESPRIT method is resilient against the unknown mutual coupling matrix（MCM） and can be directly utilized to estimate the direction of departure（DOD） and the direction of arrival（DOA）.Moreover,the mutual coupling coefficient is estimated by finding the solution of the linear constrained optimization problem.The proposed method allows an efficient DOD and DOA estimates with automatic pairing.Simulation results are presented to verify the effectiveness of the proposed method.
基金Supported by the 2010 Natural Science Foundation of Shanghai (No. 09ZR1430400)
文摘Anovel compact E shape High Impedance Surface(HIS) Electromagnetic Band-Gap(EBG) comprising Amended Minkowski Fractal Boundary(AMFB),Added Metal Strips(AMS),and metal plated via printed on a Rogers TMM 10i substrate is presented.The first order AMFB and ABS are introduced for equivalent capacitance enhancement and miniaturization with effective space-filling characteristics.The dimension of lattice size is only The proposed structure exhibits a most compact characteristic about 35% size reduction as compared with conven-tional mushroom-like HIS-EBG,and better surface-wave decoupling of around 9 dB at the operating frequency band.Details of design parameters which affect the whole performance of certain band-gap are intensively investigated.A constructed prototype is potential candidate for antenna system per-formance enhancement.
基金Supported by the Innovation Foundation for Outstanding Postgraduates in the Electronic Engineering Institute of PLA (No. 2009YB005)
文摘A novel Direction-Of-Arrival (DOA) estimation method is proposed in the presence of mutual coupling using the joint sparse recovery. In the proposed method, the eigenvector corresponding to the maximum eigenvalue of covariance matrix of array measurement is viewed as the signal to be represented. By exploiting the geometrical property in steering vectors and the symmetric Toeplitz structure of Mutual Coupling Matrix (MCM), the redundant dictionaries containing the DOA information are constructed. Consequently, the optimization model based on joint sparse recovery is built and then is solved through Second Order Cone Program (SOCP) and Interior Point Method (IPM). The DOA estimates are gotten according to the positions of nonzeros elements. At last, computer simulations demonstrate the excellent performance of the proposed method.
基金the National High Technology Research and Development Program of China (2002AA123032)
文摘A new and exact calculation method for the mutual impedance matrix of receiving arrays is proposed. The mutual impedance matrix is derived from electromagnetic boundary conditions and can be used to relate the coupling free open-circuit voltages, instead of the conventional ones, to the measured voltages. A remarkable improvement on compensation for the coupling effects is shown in the direction finding applications, while a simple relationship between measured terminal voltages and the coupling free voltages is remained.
基金supported by the National Natural Science Foundation of China (No. 61302141)
文摘In this paper, a novel algorithm is presented for direction of arrival（DOA） estimation and array self-calibration in the presence of unknown mutual coupling. In order to highlight the relationship between the array output and mutual coupling coefficients, we present a novel model of the array output with the unknown mutual coupling coefficients. Based on this model, we use the space alternating generalized expectation-maximization（SAGE） algorithm to jointly estimate the DOA parameters and the mutual coupling coefficients. Unlike many existing counterparts, our method requires neither calibration sources nor initial calibration information. At the same time,our proposed method inherits the characteristics of good convergence and high estimation precision of the SAGE algorithm. By numerical experiments we demonstrate that our proposed method outperforms the existing method for DOA estimation and mutual coupling calibration.
文摘A novel compact Swastika shaped patch antenna is designed in the present work,which can be used for Multiple Input Multiple Output(MIMO) systems.The proposed two element MIMO system resonates at a triband of 3.3 GHz,5.8 GHz,and 7.1 GHz with an improved impedance bandwidth of 37% and a reduced mutual coupling of-33 dB.These results are better compared to a normal E shaped patch antenna designed with same size and thickness,achieved without using any additional decoupling methods.A 2×2 MIMO system employing the Swastika shaped patch antennas is analyzed using computational electromagnetic ray tracing software for an indoor environment.The results show an improvement in the capacity compared to a 2×2 MIMO system developed with dipole antennas.The proposed antenna is a good choice for MIMO systems operating for several Ultra WideBand(UWB) applications.
基金Qingdao Basic Research of Science and Technology Plan Projects(No.13-1-4-132-jch)
文摘A mutual coupling suppression method is proposed for microstrip antenna array by cutting four small semi-circle annular apertures on the metal plate. The structure of antenna array is composed of 2 × 2 four elements. The antenna consists of double layer dielectric, and it realizes circular polarization characteristics by cutting rectangular slot on circular patch in the direction of 45°, by using aperture coupling feeding and reverse feeding principle. There is 90＊ phase difference between adjacent antenna elements. Thus, it cuts off the coupling current field between the elements, suppresses the surface wave and reduces the mutual coupling by cutting four semi-circle annular apertures symmetrically on the metal plate. The simulation results show that after cutting four semi-circle annular apertures, the antenna array coupling coefficients decrease significantly, and the side and back lobe levels are suppressed effectively with the gain of antenna improved. So the proposed method is effective to suppress microstrip antenna array mutual coupling.
基金Supported by National High Technology Research and Development Program of China (No. 2002AA123032)
文摘A unified mutual coupling model for multiple antenna communication systems based on moment methods is proposed. This model combines antenna coupling and RF front-end circuit coupling, thus providing a more accurate and complete analysis of the mutual coupling effect on multiple antenna systems.
基金Project(61201381)supported by the National Natural Science Foundation of ChinaProject(YP12JJ202057)supported by the Future Development Foundation of Zhengzhou Information Science and Technology College,China
文摘The sensor array calibration methods tailored to uniform rectangular array(URA)in the presence of mutual coupling and sensor gain-and-phase errors were addressed.First,the mutual coupling model of the URA was studied,and then a set of steering vectors corresponding to distinct locations were numerically computed with the help of several time-disjoint auxiliary sources with known directions.Then,the optimization modeling with respect to the array error matrix(defined by the product of mutual coupling matrix and sensor gain-and-phase errors matrix)was constructed.Two preferable algorithms(called algorithm I and algorithm II)were developed to minimize the cost function.In algorithm I,the array error matrix was regarded as a whole parameter to be estimated,and the exact solution was available.Compared to some existing algorithms with the similar computation framework,algorithm I can make full use of the potentially linear characteristics of URA's error matrix,thus,the calibration precision was obviously enhanced.In algorithm II,the array error matrix was decomposed into two matrix parameters to be optimized.Compared to algorithm I,it can further decrease the number of unknowns and,thereby,yield better estimation accuracy.However,algorithm II was incapable of producing the closed-form solution and the iteration operation was unavoidable.Simulation results validate the excellent performances of the two novel algorithms compared to some existing calibration algorithms.
文摘Based on the integral equation formulations and the moment method, a novel closed form solution for analyzing the mutual coupling effect between the cylindrical comformal rectangular microstrip patch antennas is presented. By using this algorithm, the elements of the impedance matrix and exciting vector are cast into closed forms, thus the computational efficiency is improved dramatically. Numerical results are presented to verify the validity and reliability of the algorithm.
文摘A4-port multiple-input multiple-output(MIMO)antenna exhibiting lowmutual coupling andUWBperformance is developed.The octagonal-shaped four-antenna elements are connected with a 50microstrip feed line that is arranged rotationally to achieve the orthogonal polarization for improving the MIMO system performance.The antenna has a wideband impedance bandwidth of 7.5GHz with S11<−10 dB from(103.44%)3.5–11GHz and inter-element isolation higher than 20 dB.Antenna validation is carried out by verifying the simulated and measured results after fabricating the antenna.The results in the form of omnidirectional radiation patterns,peak gain(≥4 dBi),and Envelope Correlation Coefficient(ECC)(≤0.01)are extracted to validate the suggested antenna performance.Aswell,time-domain analysis was investigated to demonstrate the operation of the suggested antenna in wideband applications.Finally,the simulated and experimental outcomes have almost similar tendenciesmaking the antenna suitable for its use in UWBMIMOapplications.
基金The authors extend their appreciation to the Deanship of Scientific Research at Imam Mohammad Ibn Saud Islamic University for funding this work through Research Group No.RG-21-12-08.
文摘This work provides the design and analysis of a single layer,linearly polarized millimeter wave reflectarray antenna with mutual coupling optimization.Detailed analysis was carried out at 26GHz design frequency using the simulations of the reflectarray unit cells as well as the periodic reflectarray antenna.The simulated results were verified by the scattering parameter and far-fieldmeasurements of the unit cell and periodic arrays,respectively.Aclose agreement between the simulated and measured results was observed in all the cases.Apart from the unit cells and reflectarray,the waveguide and horn antenna were also fabricated to be used in the measurements.The measured scattering parameter results of the proposed circular ring unit cells provided a maximum reflection loss of 2.8 dB with phase errors below 10°.On the other hand,the measured far-field results of the 20×20 reflectarray antenna provided a maximum gain of 26.45 dB with a maximum 3 dB beam width of 12°and 1 dB gain drop bandwidth of 13.1%.The performance demonstrated by the proposed reflectarray antenna makes it a potential candidate to be used in modern-day applications such as 5th Generation(5G)and 6th Generation(6G)communication systems.
文摘Using the Method of Moments(MoM) and the spectral method, the effect of mutual coupling on the performance of adaptive arrays is compensated. First, the MoM is used to compute the behavior of the array, where the accurate analytical model and odd numbers of piecewise sinusoids are applied. Then the covariance matrix with mutual coupling being taken into account is analyzed, and the expression for the weight of the Least Mean Square(LMS) algorithm with mutual coupling being compensated is given. Finally, the method given in this letter is tested on an example.
文摘An effective method is introduced to compensate the effects of mutual coupling for the Estimation of Signal Parameter via Rotational Invariance Techniques (ESPRIT) direction finding algorithm in application of signal snapshot array processing.Changing the covariance matrix into a Teoplitz matrix can achieve high resolution in the Direction Of Arrive (DOA) estimation.How the mutual coupling affects the array antennas has been discussed and a new definition of mutual im- pedance has been used to characterize the mutual coupling effects between the array elements.Based on the new mutual impedance matrix,a practical method is presented to eliminate the effects of mutual coupling for ESPRIT in the single snapshot data processing.The simulation results show that, this new method not only properly reduces the effects of mutual coupling,but also maintains its steady performance even for weak signals.
文摘The number of wireless electronic gadgets used in mobile communication, vehicle collision avoidance system, compact radars, etc. is extremely increasing at a rapid rate. Thus, the characteristics of the antennas involved in these gadgets are to be designed very stringently so as to avoid interferences & coupling and to improve compatibility, susceptibility, etc. Compact smart antenna with improved performance is highly essential to meet this challenging scenario. Mutual coupling between various elements of an array is one of the main factors which can be considered for improvement of performance of the antenna. Influence of mutual coupling on performance of the antenna is considered in this paper and various techniques to minimize this effect are presented. Effect of mutual coupling on radiation characteristics of the antenna can be compensated employing various methods like Conventional Mutual Impedance (CMI), Receiving Mutual Impedance (RMI). Analysis is presented as comparison between the two methods for different number of elements in the array. Analysis is also presented for different geometries of the array like circular and elliptical for improved performance. The results show performance improvement in the proposed array for parameters like SNR and Speed of convergence.
