二維相位陣列天線系統之波束切換與波束掃描技術結合

Abstract

本文中，提出一套由十六路次陣列天線所組成的波束成型(Beam-forming)系統，其中，每一路次陣列天線包含四個孔隙耦合微帶天線。次陣列天線可透過調整天線單元間的相位差，將波束切換(Switched-beam)於九個子區域(Zone)中。此外，當十六路次陣列天線的波束指向於同一子區域時，藉由調整次陣列天線間的相角差，於子區域實現連續性動態波束掃描(Beam-steering)。 提到波束成型系統，陣列系統間的相角校正將會是一重要的議題。本文中，為了解決次陣列天線間的相角偏差，系統於每一路次陣列天線的饋入訊號耦合出部分能量，並將訊號降頻至基頻。經由反饋機制，控制次陣列天線中相移器的電壓，實現十六路次陣列天線的相角校正。 此套相位陣列天線系統可用在點對點的微波或毫米波通訊，藉由波束掃描技術解決收發一直線的問題。另外，可透過系統的波束成型功能，形成一個指向通訊用戶端的高指向性輻射場型，進而提升接收端用戶的訊雜比與通訊容量。

In this work, we developed a beam-forming system consisting of sixteen subarray antennas, each containing four aperture coupled patch antennas. Each of the subarray antenna is able to switch its beam pattern toward one of the nine zones over the half-space by adjusting the specific phase delay angles among the four elements. Furthermore, once all the subarrays are pointing at the same zone, a continuous beam-steering can be achieved by dynamically altering the progressive phase delay angle among the subarrays. As far as a beam-forming system is concerned, the phase angle calibration of the array system is an extremely important issue. In this study, we couple a small portion of signal fed to each subarray and down-convert it into baseband for monitoring the phase angle deviation among the subarrays. A feedback control is subsequently carried out to tune the voltage of phase shifters for phase calibration. Such a phased-array system can be applied in the point-to-point microwave or millimeter wave link. Specifically, the problem of alignment can be resolved by incorporating the beam-steering scheme. Moreover, its beam-forming function can generate a high directional radiation pattern toward the mobile user for further enhancing the receiver signal-to-noise ratio (SNR) and channel capacity accordingly.