In antenna arrays, mutual coupling between antenna elements is well known as an undesired effect, which degrades the performance of array signal-processing algorithms. The compensation of such an undesired effect has been a popular research topic throughout the years. Various approaches for mutual-coupling compensation have been developed, and they can easily be found in the open literature. In general, the mutual-coupling problems for a transmitting and receiving array are different, even if the physical geometry of the array remains unchanged. However, it seems that antenna engineers are not well aware of such differences in the analysis of receiving antenna arrays. In this note, the mutual-coupling problems in transmitting and receiving antenna arrays are revisited. The differences between the mutual coupling and mutual impedances for transmitting and receiving antenna arrays are explained. It is concluded that the mutual-coupling problems of transmitting and receiving arrays are in general different, and hence different mutual impedances should be used for mutual-coupling analysis and compensation.

An experimental study is performed to investigate the improvement of direction-of-arrival (DOA) estimation using the recently proposed receiving mutual impedances for mutual coupling compensation. A seven-monopole antenna array is constructed and used in DOA estimation employing the MUSIC algorithm. Comparisons are made with the case of using the conventional mutual impedances for mutual coupling compensation. All experiments are carried out inside an anechoic chamber. Results are obtained for one- and two-source experiments which indicate that the performance of DOA estimation in the presence of mutual coupling can be significantly improved when the mutual coupling effect is compensated by using the receiving mutual impedances.

A short review of the receiving-mutual-impedance method (RMIM) for mutual coupling compensation in direction finding applications using linear array is conducted. The differences between the conventional-mutual-impedance method (CMIM) and RMIM, as well as the three different determination methods for receiving mutual impedance (RMI), will be discussed in details. As an example, direction finding with better accuracies is used for demonstrating the superiority of mutual coupling compensation using RMIM.

Resonance based radar target recognition using the extinction pulse (E-pulse) technique was first implemented in the mid 1980s. Various derivatives of the E-pulse technique itself as well as the associated problems of identification and differentiation have been reported throughout the literature. In this paper a modified version of the E-pulse, termed the "banded" E-pulse technique is introduced as an alternative tool for target identification

Performance degradation due to the mutual coupling effect of antenna arrays in direction-of-arrival (DOA) estimations has been well known, and many mutual coupling compensation methods have been pr...

This communication presents a novel method for determining the commencement of the late-time resonant response of a radar target, without a priori knowledge of the target geometry or orientation. Insights from Kronecker's theorem for Hankel matrices are used to determine the offset for the processing window for extraction of the true complex natural resonances by exploiting characteristic changes in the Hankel matrix, including the matrix rank and the distribution of eigenvalues. Results are presented for both simulated and measured targets.