全極化可調式之環形槽孔天線設計

Abstract

本論文旨在探討一個極化分集可調式天線之研製，應用於室內無線區域網路傳輸裝置IEEE802.11n/ac。首先，我們提出一個具有四個槽孔以及一個二極體的環形槽孔天線(Annular Ring Slot Antenna)，此天線經由二極體的狀態以及饋入位置的切換，可以達到四種不同極化的目的，以對應接收端極化未知的情形，且使用在1.6mm的FR4板材(介電常數4.4)，增加實作便利性。本論文提出設計的過程以及方法，天線的參數分析及模擬與量測的比較。 最後在實作與量測的部分，我們將其分為三種情況，一種為固定極化情況，利用理想的開路短路來做驗證其概念是否可行，另一種為有加二極體以及相關的偏壓電路，藉由適當地給予偏壓，我們可以控制二極體的導通與否，來達到切換極化的目的，使得訊號有更多的調變空間，且在二極體的部分會再用TRL確認其二極體的等效模型以及相關校準，最後一種情況為安裝開關IC ，藉由開關IC來切換不同的饋入位置，來完成整個設計。

This thesis presents a reconfigurable antenna with full polarization diversity for indoor WLAN IEEE802.11n/ac applications. First, we proposed the annular ring slot antenna with four small apertures where an aperture is loaded with a diode. By controlling only one diode and the feed line location, the proposed antenna can achieve the full polarization configurations – V-pol, H-pol, RCP, and LCP. The design concept was verified by HFSS simulation and implemented on a 1.6mm thick -FR4 PCB. This thesis provides the design procedures, parameter study, and performance comparison between the simulation and measurement. Second, we realized the prototypes with three progressive phases. In Phase 1, we used different layouts on the printed antennas to build individual antennas of various fixed polarizations. In Phase 2, we added a diode to one of the small apertures and employed the bias circuit to control between the linear and the circular polarization of a feed line. To achieve better AR of circular polarization, we used the TRL calibration method to extract the accurate circuit parameters of the employed diode. In Phase 3, we added a switch IC for the feed lines of orthogonal orientation to achieve a reconfigurable design of full polarization diversity.