射频电流导引结构应用于可切换式天线辐射场形及改善天线SAR特性.PDF

射頻電流導引結構應用於可切換式天線輻射場形 及改善天線SAR特性 RF Current Dragger for Reconfigurable Antenna Pattern and Improving SAR Characteristic 浦 大 鈞 陳 叡 宏 吳 俊 熠 林 弘 萱 Ta-Chun Pu, Jui-Hung Chen, Chun-Yih Wu, Hung-Hsuan Lin 中文摘要 本文將介紹一種具有可切換多種輻射場形之天線結構，這種天線結構是由主動天線與電流導 引結構組成。我們將天線接地面視為天線輻射體的一部分，因此只要能控制天線接地面上射頻電 流分布，便可以改變天線之輻射場形。電流導引結構就本質上是屬於一種偽天線或是低Q值共振 器的電磁結構，裝置於天線接地面上，藉由控制器來切換射頻電 入此結構與否來決定接地面 上之射頻電流分布。不同切換組合使天線具切換不同輻射場形之特性。此外，由於電流導引結構 可以改變接地面電流分布，我們可以藉由改變天線近場能量分布而改善天線SAR特性。 Abstract In this article, we will introduce an antenna structure with reconfigurable pattern, which comprising an active antenna and current draggers. We treat the antenna ground as a part of the radiator. Therefore, controlling the RF current on antenna ground can manipulate the radiation pattern of the antenna. The current dragger, which intrinsically is a kind of pseudo antenna or a low-Q resonator, is installed on the antenna ground. With a controller and switches, we can change the RF current distribution by enabling or disabling the current draggers. Antenna shows different radiation pattern with different switching configurations of the current draggers. Besides, the RF current distribution on the antenna ground is changed by the current dragger, the near-field EM energy could be re-distributed and the SAR characteristic also could be improved. TAO 關鍵詞(Key Words) 射頻電流導引裝置 (RF Current Dragger) 智慧型天線 (Smart Antenna) 多進多出天線技術 (MIMO Antenna) 自適應天線系統 (Adaptive Antenna System) 電磁波能量比吸收率 (Specific Absorption Rate ；SAR) １．前言 一環，最主要可分為多進多出天線技術(MIMO) 以及自適應天線系統(AAS)兩大類別。MIMO 天 在天線設計方面，智慧型天線 (smart