Mutual Coupling Matrix Research Articles

Robust DOA estimation and array calibration in the presence of mutual coupling for uniform linear array

The presence of unknown mutual coupling between array elements is known to significantly degrade the performance of most high-resolution direction of arrival (DOA) estimation algorithms. In this paper, a robust subspace-based DOA estimation and array auto-calibration algorithm is proposed for uniformly linear array (ULA), when the array mutual coupling is present. Based on a banded symmetric Toeplitz matrix model for the mutual coupling of ULA, the algorithm provides an accurate and high-resolution DOA estimate without any knowledge of the array mutual couplings. Moreover, a favorable estimate of mutual coupling matrix can also be achieved simultaneously for array auto-calibration. The algorithm is realized just via one-dimensional search or polynomial rooting, with no multidimensional nonlinear search or convergence burden involved. The problem of parameter ambiguity, statistically consistence and efficiency of the new estimator are also analyzed. Monte-Carlo simulation results are also provided to demonstrate the effectiveness and behavior of the proposed algorithm.

Effects of mutual coupling on the performance of STAP antenna arrays

The effect of mutual coupling on the performance of space-time adaptive processing (STAP) antenna arrays is investigated. A signal model that includes the effects of mutual coupling is derived and used to compute the optimum solution for the fully adaptive and a variety of partially adaptive algorithms. The simulations indicate that if the mutual coupling is not properly accounted for there is significant degradation of the signal-to-interference-plus-noise ratio (SINR). In addition, the clutter notch is widened resulting in a larger minimum detectable velocity (MDV) of the target. When the mutual coupling is properly accounted for, the performance can be restored to the ideal level. However, STAP algorithms, in general, are very sensitive to errors in the mutual coupling matrix, requiring a very complete knowledge of this matrix for good performance. Of all the algorithms considered here, beam space algorithms appear to be the most robust with respect to uncertainties in the mutual coupling matrix.

Arbitrarily-Shaped Slot-Coupled Microstrips and Their Applications in Microwave Integrated Circuits and Antennas

Abstract The mixed-potential integral equation (MPIE) is solved by the method of moments in order to investigate arbitrarily-shaped slot-coupled microstrip discontinuity problems. A concise expression of the mutual coupling matrix element is utilized to assure numerical efficiency and accuracy. Comparison between this MPIE and other moment methods (such as MFIE and EFIE) is also carried out and discussed. In order to validate this modeling tool, a circularly polarized dual slot-coupled patch antenna and a single slot-coupled directional coupler arc investigated. Good agreement between numerical results and measurement is achieved. Two examples of dual slot-coupled patch antenna and annular ring slot antenna with microstrip line feed arc designed to provide desired circularly polarized radiation. In addition, a weak coupling slot-coupled directional coupler is designed by utilizing a pair of circular slots. Good performance for directivity, isolation, and return loss is obtained.