波束可調之雙波束反射陣列設計

本論文提出了一個新穎的波束可調之雙波束反射陣列天線系統，這個反射陣列係利用六角形的單元以蜂窩狀排列而成，每一個單元皆由一背覆金屬之帶狀偶極及其中央負載之變容二極體所組成，接上此負載之用途在於可動態地調整單元的反射相位。為了找出反射陣列上合適的相位分布以調整雙波束各自之方向，本論文先提出一個理想分析相位分布的演算法，以作為相位分布起始值參考，並且與所設計的反射陣列架構整合，反射陣列裡的每一列都可視為一線性子陣列，並且可透過利用理想分析得到參考最佳解。每一子陣列可將其組成單元分成奇數單元和偶數單元兩種，分別用以產生兩個指定方向之主波束，並且各別對兩類單元進行最佳化。為了補償實際反射陣列的非完美週期性，我們針對位於反射陣列邊緣的單元，提出一個簡單的反射相位修正方法，當反射陣列之邊緣單元採用此修正後的相位分布，其場型將更接近理想分析所得到的解。最後，我們提出了一個基於基因演算法的方法，可用來修正實際反射陣列每個反射單元的反射相位以達到最佳化的效果。本論文所提出之反射陣列的操作頻率會受到反射單元的工作頻率範圍以及變容二極體可調容值範圍之限制，而反射陣列的大小與其反射單元的總數則是受到基板板材大小及接線盒(將於第二章第三節提到)所能提供接線端的埠數的限制。因此，在本論文的實驗驗證部分，我們提出並實作一款操作在5.8 GHz，由91個所設計的六邊形反射單元所組成的波束可調之雙波束反射陣列。其雙波束之間的角度差範圍最大可以達到60度，在不低於30度的情況下，場型較佳。此波束可調反射陣列的最高增益介於7.1到12.1 dBi之間，孔徑效率可以達到66%。在5.77至5.83的頻段中，其中之一的波束衰減量會小於3 dB。

關鍵字

雙波束；波束可調；反射陣列；最佳化演算法

並列摘要

A novel beam-steerable dual-beam reflectarray antenna system is presented. It consists of hexagonal unit cells arranged in a honeycomb lattice structure. Each unit cell is formed by a conductor-backed strip dipole loaded with a varactor diode for adaptively adjusting its reflection phase. To find the appropriate phase distribution for the unit cells, an ideal analysis algorithm is proposed and integrated with the reflectarray structure. Each row of the reflectarray can be considered as a linear subarray and is optimized by the ideal analysis. In each subarray, the even and odd numbers of the unit cells are configured respectively for the two targeted beams, and optimized separately. To account for the imperfect periodic boundary condition of the prototype reflectarray, a method is proposed to correct the reflection phases of the unit cells at the outer rim of the reflectarray. At last, a Genetic-Algorithm-based (GA-based) phase correction method is proposed and is adopted to correct the preliminary reflection phase of each unit cell obtained from the ideal analysis. The operating frequency range of the proposed reflectarray is limited by the operating frequency/bandwidth of the unit cell in use and the available tuning range of the varactor diode. Moreover, the total area of the prototype reflectarray is limited by the fabrication process and the maximum size of the available dielectric slab, and the number of unit cells in the reflectarray is limited by number of I/O ports of the DAQ interface (as will be detailed in Section 3 of Chapter 2). Therefore, a 91-element beam-steerable dual-beam reflectarray operating at 5.8 GHz with configured hexagonal unit cell is proposed, fabricated, and tested. The angle between the dual beams can be up to 60. Moreover, if the angle is not less than 30, the reflected field is better. The maximal gain of the proposed beam-steerable reflectarray is between 7.1 dBi and 12.1 dBi and the aperture efficiency can reach 66%. The loss of one of the targeted beams is lower than 3 dB in the bandwidth from 5.77 GHz to 5.83 GHz.

並列關鍵字

beam-steerable ； dual-beam ； reflectarrays ； optimization algorithm

參考文獻

[1] R. Deng, S. Xu, and F. Yang, "Design of a Ku/Ka quad-band reflectarray antenna for satellite communications," in Proc. IEEE AP-S Int. Symp. and URSI Radio Sci. Meeting, Fajardo, Puerto Rico, Jun. 2016, pp. 1217-1218.

[2] O. M. Haraz and M. M. M. Ali, "A millimeter-wave circular reflectarray antenna for future 5G cellular networks," in Proc. IEEE AP-S Int. Symp. and URSI Radio Sci. Meeting, BC, Canada, Jul. 2015, pp.1534-1535.

[3] R. E. Hodges, et al., "A Deployable High-Gain Antenna Bound for Mars: Developing a new folded-panel reflectarray for the first CubeSat mission to Mars," IEEE Antennas and Propag. Mag., vol. 59, no. 2, pp. 39-49, Apr. 2017.

[5] Q. L. Yang, et al., "SIW Multibeam Array for 5G Mobile Devices," IEEE Access, vol. 4, pp. 2788-2796, Jun. 2016.

[6] T. Maruyama, et al., "Design of multi-beam reflectarray using mushroom-like structure," in Proc. IEEE AP-S Int. Symp. and URSI Radio Sci. Meeting, Orlando, Florida, Jul. 2013, pp.1352-1353.

國際替代計量

波束可調之雙波束反射陣列設計

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