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An Imaging Method With array factor synthesis in Synthetic Aperture Interferometric Radiometers

IEEE GEOSCIENCE AND REMOTE SENSING LETTERS 2016年第1期13卷 87-91页

作者： Li, Jun Hu, Fei He, Feng Wu, Liang Peng, Xiaohui Zhu, Dong Huazhong Univ Sci & Technol Sch Elect Informat & Commun Wuhan 430074 Peoples R China Huazhong Univ Sci & Technol Natl Key Lab Sci & Technol Multispectral Informat Wuhan 430074 Peoples R China

In this letter, an imaging method with array factor synthesis in synthetic aperture interferometric radiometers (SAIRs) is presented. The presented method can efficiently control the characteristics of the equivalent array factor of SAIR, such as null position and depth, sidelobe level, and so on, which will be beneficial in the presence of potential interferences, such as radio frequency interference. The method is based on the formulation that the SAIR array is equivalent to a phased array with a virtual antenna element located in each baseline. The previous built-in method and the conventional Fourier inverse method can be seen as a special case of the presented one. Numerical results validate the effectiveness of the presented method.

关键词： array factor synthesis imaging interference suppression synthetic aperture radiometry

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SMOS RFI MITIGATION USING array factor synthesis OF SYNTHETIC APERTURE INTERFEROMETRIC RADIOMETRY 36

SMOS RFI MITIGATION USING ARRAY FACTOR SYNTHESIS OF SYNTHETI...

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36th IEEE International Geoscience and Remote Sensing Symposium (IGARSS)

作者： Li, Jun Hu, Fei He, Feng Wu, Liang Peng, Xiaohui Huazhong Univ Sci & Technol Sch Elect Informat & Commun Wuhan 430074 Peoples R China Huazhong Univ Sci & Technol Natl Key Lab Sci & Technol Multispectral Informat Wuhan 430074 Peoples R China

ISBN: (纸本)9781509033324

Radio frequency interference (RFI) is one of the most significant limiting factors in the retrieval of geophysical parameters measured by microwave radiometers. In this work, based on the measured visibilities of European Space Agency's Soil Moisture and Ocean Salinity (SMOS) mission, RFI mitigation results are presented using two approaches of array factor synthesis of synthetic aperture interferometric radiometry, i.e., RFI mitigation based on null control and low sidelobe synthesis. Results show that, for the approach of array factor synthesis with null control, the Gibbs-like contamination of weak and moderate RFIs can be mitigated very well, but it is not enough effective for strong RFIs because of instrument errors. On the other hand, for strong RFIs, at the cost of spatial resolution degradation which may be not critical for ocean salinity retrieval, result shows the approach of low sidelobe synthesis can be effective to mitigate the Gibbs-like contamination of strong RFIs.

关键词： array factor synthesis microwave radiometry Radio Frequency Interference (RFI) Soil Moisture and Ocean Salinity (SMOS) mission aperture synthetic radiometry

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Grating Lobe Suppression With Discrete Dipole Element Antenna arrays

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IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS 2016年 15卷 1234-1237页

作者： Chakravorty, Pragnan Mandal, Durbadal Natl Inst Technol Durgapur Dept Elect & Commun Engn Durgapur 713209 India

Antenna arrays with interelement spacing as integral multiple of wavelength lambda have been absent in practical implementations despite their highly directive main lobe;the disuse is primarily attributed to the presence of grating lobes. This letter proposes a modification in a linear antenna array whereby the grating lobes are suppressed by up to 100% with an additional improvement in the directivity of main-lobe and reduction in other sidelobe levels. A new array factor is synthesized by replacing the individual elements in a linear array with a pair of elements called discrete dipole elements (DDEs);a background theory of spatial hard windowing is proposed for the synthesis of array factor. array factors of linear array made of eight DDEs are compared to those of an eight-element linear isotropic array to validate the claims. The proposed DDE array is then fabricated using monopole antennas;a good agreement between measured, simulated, and analytical results is seen.

关键词： Antenna theory array factor synthesis discrete dipole array grating lobe suppression

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Differential evolution algorithm applied to sidelobe level reduction on a planar array

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AEU-INTERNATIONAL JOURNAL OF ELECTRONICS AND COMMUNICATIONS 2007年第5期61卷 286-290页

作者： Rocha-Alicano, Carlos Covarrubias-Rosales, David Brizuela-Rodriguez, Carlos Panduro-Mendoza, Marco CICESE Res Ctr Ensenada 22860 Baja California Mexico Autonomous Univ Tamaulipas Reynosa Rhode Acad Ctr Reynosa Mexico

In this paper, differential evolution (DE), one of the youngest paradigms in evolutionary computation, is applied to the process of synthesizing a planar array factor focused on sidelobe-level reduction. Sidelobe level is a critical array factor parameter in the task of reducing background noise and interference in the most recent Wireless Communications Systems. Minimization of sidelobe level involves nonlinear and non-convex dependence between array factor and its elements parameters becoming a highly complex problem. However, DE has proven to be a fast and efficient algorithm for complex real-valued problems. Subsequently, a binary-coded genetic algorithm is proposed for the synthesis of planar arrays. Numerical results show a promising performance ofDE reducing noticeably the sidelobe level generated by a uniform planar array. (C) 2006 Elsevier GmbH. All rights reserved.

关键词： planar array differential evolution algorithm array factor synthesis

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Element Selection for Partial Adaptive Nulling

Element Selection for Partial Adaptive Nulling

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2010 IEEE International Symposium Antennas and Propagation/CNC-USNC/URSI Radio Science Meeting

作者： Haupt, Randy L. Penn State Univ Appl Res Lab State Coll PA 16801 USA

ISBN: (纸本)9781424449682

The cancellation patterns were found analytically for array factors synthesized from isotropic point sources and numerically for adaptive dipole arrays. Decreasing the number of adaptive elements and/or decreasing the range of the adaptive weights results in more pattern distortion. This approach can be used to find the cancellation patterns of experimental adapted patterns.

关键词： adaptive antenna arrays adaptive dipole antenna arrays adaptive weights array factor synthesis dipole antenna arrays experimental adapted patterns isotropic point sources matrix algebra partial adaptive nulling pattern cancellation pattern distortion

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Development of an analytical method for pattern synthesizing of linear and planar arrays with optimal parameters

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AEU-INTERNATIONAL JOURNAL OF ELECTRONICS AND COMMUNICATIONS 2022年 146卷

作者： Tamandani, Abdolshakoor Alijani, Mohammad G. H. Velayat Univ Fac Engn Iranshahr Iran Ferdwosi Univ Mashhad Elect Dept Mashhad Iran

Typically, in the synthesis problem of an equally-spaced array, the number of array elements and the element spacing should be specified before. In this paper, based-on the Nyquist-Shannon sampling theorem, a new procedure is introduced, which is used in choosing the optimal value of the number of array elements and the element distance. After specifying the number of array elements and the element spacing, an analytical method based-on the integral transform with the Gegenbauer kernel is used for the calculation of the excitation weights of the array. Also, directivity, amplitude dynamic range and mutual coupling considerations are regarded in the introduced procedure. Additionally, it is shown that the proposed method can be developed for planar and ring arrays. Several test cases with special features are examined to verify the performance of the presented method.

关键词： Antenna arrays array factor synthesis Gegenbauer polynomial

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A new noniterative method for pattern synthesis of unequally spaced linear arrays

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INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING 2019年第11期29卷 e21921-e21921页

作者： Alijani, Mohammad C. H. Neshati, Mohammad H. Ferdwosi Univ Mashhad Elect Dept Mashhad Razavi Khorasan Iran

In this article, a new noniterative beam shaping method is introduced to synthesise array factor (AF) of an unequally spaced linear array (UESLA). The proposed method is based on eigenvector decomposition of sampled data matrix of a given pattern. Using matrix analysis, the eigenvalues and their corresponding eigenvectors of the sampled matrix are determined. It is shown that the eigenvalues and eigenvectors of the sampled matrix are related to the locations and complex excitation coefficients of the array elements. According to the concept of generalized eigenvalue concept, the solution of locations and excitation coefficients is derived using least square method. In order to reduce the number of array elements, singular value decomposition is applied to obtain a low ranked matrix using rejection of nonzero eigenvalues. Using the approximated sampled matrix, the excitation and locations of the optimized array elements are calculated. A few comprehensive examples are investigated to verify the accuracy of the proposed method and the obtained results are compared with those of an equally spaced linear array (ESLA). It is shown that the total number of array elements in an UESLA is less than that of ESLA, which is the most advantage of the introduced method in AF synthesis.

关键词： antenna array array factor synthesis unequally spaced linear array

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Development of a new method for pattern synthesizing of the concentric ring arrays with minimum number of rings

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AEU-INTERNATIONAL JOURNAL OF ELECTRONICS AND COMMUNICATIONS 2022年 152卷

作者： Alijani, Mohammad G. H. Tamandani, Abdolshakoor Velayat Univ Fac Engn Iranshahr Iran Ferdwosi Univ Mashhad Elect Dept Mashhad Iran

In this paper, a new method is proposed for pattern synthesizing of the concentric ring arrays with minimum number of rings. The method is established based on a hybrid combination of the conventional least square method and the Richardson technique. Using a sampling function, a system of linear equations is created. After that, using the QR factorization and Richardson techniques, the complex excitation coefficients of the array elements are obtained. Furthermore, it is shown that using a simple try and error process, the number of array rings can be reduced. To verify the accuracy and the advantages of the proposed technique, a few well-known patterns are investigated and the obtained results are compared.

关键词： Concentric ring array array factor synthesis Richardson method

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