摘要
波束形成算法和天线阵列是智能天线系统的两个重要组成部分。对来波的波达方向(DOA, Direction of Arrival)进行正确估计是DOA波束形成算法的前提条件。用微带阵列实现智能天线能够满足系统小型化、造价低的要求，这在现代通信中有着广泛地应用前景。在实际应用中，DOA估计通常是二维问题，互耦会降低DOA估计的精度，必须进行补偿。本文首先对两种二维DOA估计算法—SSM法和二维酉ESPRIT法的性能进行了比较，用空域平滑算法解决了相干源的二维DOA估计；其次运用腔模理论计算微带天线的自阻抗，用反应原理计算微带天线间的互阻抗，进而形成计入互耦影响的广义阻抗矩阵；讨论了互耦对二维DOA估计的影响，提出了两种互耦补偿的方法。
The beamforming algorithm and antenna array are two important parts of smart antenna systems. The correct estimation of incident signals' direction of arrivals (DOAs) is the premise of DOA-based beamforming algorithms. Microstrip antenna arrays can meet smart antenna's demands of miniaturization and low cost and will be used widely in modern communication systems. Practically, the DOA estimation is two- dimensional (2-D) and is affected by mutual coupling, which must be compensated for. First, this paper compares the performance of the signal space matrix (SSM) method with that of the 2-D unitary estimation of signal parameters via rotational invariance techniques (Unitary ESPRIT) method. To resove coherent sources, spatial smoothing approach is described. Second, we compute the self-impedance through cavity modal theory and mutual impendance based on reaction theory respectively. Then the generalized impedance matrix that reflects the effect of mutual coupling is formed. At last, the effect of mutual coupli
ng on 2-D DOA estimation algorithms is investigated and two efficient methods of mutual coupling compensation are proposed.
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