Study Of Mutual Coupling And Compensation On Array Antennas

Warfare in future is informational warfare and the earlier one can discover enemy dynamic movements, the better one would gain the initiative in the war. For shipborne over-the-horizon radar, which has long wave length, the size of receiving array antennas are usually large in order to satisfy the demands including SNR and angle measuring precision. However, the antenna miniaturization should be taken into consideration because of the limited space of ship. With the element spacing diminishing, the mutual coupling between array elements can't be ignored anymore. In this thesis, it is focused on analyzing the effects of mutual coupling and compensation on array antennas.MoM is one of the mainly methods analying the electromagnetic scattering and radiation. It can analyze thin wire antenna. In the paper, the wire antenna is modeled as a thin strip. RWG basis funcion is used to model the surface current, using Galerkin to solve electic field integral equation. Meanwhile, it introduces general impedance. Taking into account Chebyshev arrays, the effects of mutual coupling on pattern are analyzed under different situations. Simulation results show some useful conclusions.Angle measurement accuracy is a key index of array antennas. Several DOA methods are compared under coherent source and incoherent source, and results in the fact show that MUSIC and its correction are better. The mutual coupling effects on DOA algorithms are also simulated.Because mutual coupling could vary the performance of antenna array, two compensatory methods are given from two different aspects and both get good effects in imitative theories. The mutual coupling compensation in DOA estimation, reported in last literatures, ignored the effects of incident wave from different directions. Different signal directions are able to influence the array manifold, and would change both signal subspace and noise subspace. Taking MUSIC algorithm for example, the simulation indicates that second compensation should be considered as array antenna receive many signals which is from near-axes direction.