使用均勻大小平面金屬散射單元之全向性毫米波散射陣列面

A Millimeter Wave Scattering Array Surface Using Uniform Size Planar Metal Scattering Elements for Omnidirectional Scattering

王輔璟(Fu-Ching Wang)

指導教授 ： 盧信嘉

國立臺灣大學/電機資訊學院/電信工程學研究所/碩士(2022年)

https://doi.org/10.6342/NTU202202634

摘要

為了解決5G毫米波傳送時容易被障礙物阻擋而形成通訊盲區之問題，本論文提出採用相位陣列天線理論與光柵波瓣合成方法，使用相同大小金屬片的散射陣列面來實現全向性散射，本散射面不需任何主動及控制電路即可使訊號散射到室內或室外因遮蔽物或角落造成的通訊盲區，以改善服務範圍。
本論文首先介紹雷達截面積概念來描述平面金屬散射單元的散射特性。隨即提出相位陣列天線理論，進而帶入光柵波瓣現象，分析天線單元間距與光柵波瓣及零點的關係。後續再提出應用光柵波瓣合成方式，觀察不同間距所產生不同角度的光柵波瓣及零點，經由模擬結合不同間距的天線單元合成最終散射場型，並使用MATLAB Code實現陣列隨機排列演算法，以產生最後陣列佈局。根據雷達方程式來預估此散射陣列面在不同方向的散射功率，也提出使用機率密度函數及累積分布函數來做為評估散射分散程度的指標。
實際量測方面，量測系統包含兩個28GHz號角天線當作發射天線及接收天線、訊號產生器、本論文設計之散射陣列面、電控旋轉台與功率感測器所組成，驗證在有無使用散射陣列面情況下，不同角度之功率散射情形。其量測結果與理論分析模擬大致吻合。加入散射面後可改善將近15dB，且在入射方向以外±30°的改善效果更加明顯。

關鍵字

5G通訊 ； 毫米波頻段 ； 相位陣列天線 ； 光柵波瓣 ； 可重構智能反射面 ； 電波散射

並列摘要

In order to solve the blind spot caused by obstacles in 5G mmWave, this thesis presents a scattering array surface by using phased array antenna theory and grating lobe synthesis method, which can achieve omnidirectional scattering by using same-size planar metal scattering elements. This scattering array can scatter the signal to reach the indoor or outdoor communication blind area caused by shelters or corners without any active and control circuit. So the service area can be increased.
Firstly, this thesis introduces radar-cross-section (RCS) area to describe the scattering characteristics of planar metal scattering element. Secondly, we present the phased array antenna theory and grating lobes. Then we analyze the relationship between antenna elements’ spacing, grating lobes and nulls. Then, we observe the amplitude of grating lobes and nulls at different angles generated by different element spacings. The final scattering array is synthesized by combining antenna elements with random spacing, generated by MATLAB code. Based on radar equation, the scattered power in the different directions of this scattering array surface are calculated. Probability density function (PDF) and cumulative distribution function (CDF) are also used as indicators for evaluating the degree of scattering.
The measurement system includes two 28GHz horn antennas, signal generator, scattering array, rotator and power sensor. The system can verify the scattered power at different scattering angles with or without scattering array surface. The measurement results fit well with theoretical prediction. The received signal is improved by about 15dB with the scattering array, and the scattering is more effective when the signal is scattered over ±30° apart from the direct path.

並列關鍵字

fifth-generation communication system ； millimeter wave frequency ； phased array antenna ； grating lobe ； reconfigurable intelligent surfaces ； EM wave scattering

參考文獻

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