Optimizations for robust low sidelobe beamforming of bistatic multiple-input multiple-output virtual array

By utilizing a tiny frequency increment across the array elements, frequency diverse array (FDA) generates a beampattern possessing the property of range-angle-dependent. However, the beampattern of the conventional FDA is “S”-shaped, which means it is coupled in range-angle domains, resulting in low target indication accuracy and poor jamming suppression ability. In this paper, taking advantage of multiple-input multiple-output (MIMO) technique and multiple matched filters, a new FDA framework using Hamming window weighted linear frequency increments is proposed. Correct FDA-MIMO framework and multiple matched filters are used to remove the influence of the time parameter. A range-angle-decoupled beampattern with sharp pencil-shaped mainlobe and low sidelobe levels can be produced. Comparing with the existing FDA-decoupled transmit beampattern design methods, a more focusing beampattern can be achieved. Simulation results validate the superiority of the proposed system.

Download Full-text

Design and Imaging of Ground-Based Multiple-Input Multiple-Output Synthetic Aperture Radar (MIMO SAR) with Non-Collinear Arrays

10.20944/preprints201703.0090.v1 ◽

2017 ◽

Author(s):

Cheng Hu ◽

Jingyang Wang ◽

Weiming Tian ◽

Tao Zeng ◽

Rui Wang

Keyword(s):

Coupling Effect ◽

Near Field ◽

Multiple Input Multiple Output ◽

Far Field ◽

Imaging Result ◽

Multiple Input ◽

Input Multiple Output ◽

Edge Points ◽

Virtual Array ◽

Field Edge

MIMO (multiple-input multiple-output) radar provides much more flexibility than the traditional radar for its ability to realize far more observation channels than the actual number of T/R (transmit and receive) elements. Designing the array of MIMO imaging radar, the commonly used virtual array theory generally assumes that all elements are placed on the same line. However, due to the physical size of the antennas and coupling effect between T/R elements, a certain height difference between T/R arrays is essential, resulting in the defocusing of edge points of the scene. On the other hand, the virtual array theory implies far-field approximation, leading to inevitable high grating lobes in the imaging result of near-field edge points of the scene observed by common MIMO array. To tackle these problems, this paper derives the relationship between target’s PSF (point spread function) and pattern of T/R arrays, by which the design criterion of near-field imaging MIMO array is presented. Firstly, the proper height between T/R arrays is designed to focus the near-field edge points well. Secondly, the far-field array is modified to suppress the grating lobes in the near-field area. Finally, the validity of the proposed methods is verified by simulations and an experiment.

Download Full-text

Conjugate ESPRIT for MIMO Radar without Using Non-Circular Signals

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.513-517.3850 ◽

2014 ◽

Vol 513-517 ◽

pp. 3850-3854

Author(s):

Jian Feng Li ◽

Wei Yang Chen ◽

Xiao Fei Zhang

Keyword(s):

Data Model ◽

Multiple Input Multiple Output ◽

Mimo Radar ◽

Rotational Invariance ◽

Joint Estimation ◽

Signal Parameters ◽

Direction Of Departure ◽

Multiple Input ◽

Input Multiple Output ◽

Virtual Array

Without using non-circular signals, conjugate estimation of signal parameters via rotational invariance technique (ESPRIT) for joint estimation of direction of departure (DOD) and direction of arrival (DOA) in bistatic multiple-input multiple-output (MIMO) radar is proposed. The characteristics of the Vandermonde-like matrix are employed to expand the virtual array of MIMO radar. Then the rotational invariance in the signal subspace is exploited to get the automatically paired estimations of angles. The proposed algorithm works with the same data model as that of ESPRIT, and has better angle estimation performance and can detect more targets than ESPRIT. Simulation results verify the usefulness of our approach.

Download Full-text

Joint Phased-MIMO and Nested-Array Beamforming for Increased Degrees-of-Freedom

International Journal of Antennas and Propagation ◽

10.1155/2015/989517 ◽

2015 ◽

Vol 2015 ◽

pp. 1-11 ◽

Cited By ~ 3

Author(s):

Chenglong Zhu ◽

Hui Chen ◽

Huaizong Shao

Keyword(s):

Degrees Of Freedom ◽

Phased Array ◽

Multiple Input Multiple Output ◽

Doa Estimation ◽

Multiple Input ◽

Input Multiple Output ◽

Virtual Array ◽

The Difference ◽

Array Beamforming ◽

Error Simulation

Phased-multiple-input multiple-output (phased-MIMO) enjoys the advantages of MIMO virtual array and phased-array directional gain, but it gets the directional gain at a cost of reduced degrees-of-freedom (DOFs). To compensate the DOF loss, this paper proposes a joint phased-array and nested-array beamforming based on the difference coarray processing and spatial smoothing. The essence is to use a nested-array in the receiver and then fully exploit the second order statistic of the received data. In doing so, the array system offers more DOFs which means more sources can be resolved. The direction-of-arrival (DOA) estimation performance of the proposed method is evaluated by examining the root-mean-square error. Simulation results show the proposed method has significant superiorities to the existing phased-MIMO.

Download Full-text

Minimum redundancy MIMO array synthesis with a hybrid method based on cyclic difference sets and ACO

International Journal of Microwave and Wireless Technologies ◽

10.1017/s1759078715001257 ◽

2015 ◽

Vol 9 (1) ◽

pp. 35-43 ◽

Cited By ~ 3

Author(s):

Jian Dong ◽

Ronghua Shi ◽

Ying Guo

Keyword(s):

Hybrid Method ◽

Numerical Experiments ◽

Multiple Input Multiple Output ◽

Computational Cost ◽

Difference Sets ◽

Cyclic Difference Sets ◽

Multiple Input ◽

Input Multiple Output ◽

Virtual Array ◽

Array Aperture

As a recently proposed concept, multiple-input multiple-output (MIMO) radars exhibit much higher spatial resolution than traditional transmitter based radars because of the synthesized virtual array. In this paper, the problem of minimum redundancy (MR)-MIMO array synthesis is addressed, which seeks to maximize the virtual array aperture of MIMO radars for a given number of transmitting and receiving elements. A hybrid method combining autocorrelation property of cyclic difference sets (CDSs) and global search characteristics of ant colony optimization (ACO) is proposed for a rapid and numerically-effective exploration of MR-MIMO array configurations. Numerical experiments validate the proposed method, showing improvements in convergence rate and computational cost with respect to bare ACO-based search as well as improvements in the generality and configuration variety with respect to the CDS-based method.

Download Full-text