利用雙頻段雙裂環共振器抑制WiFi訊號所產生的電磁干擾

Abstract

裂環共振器可以被視為一個LC電路，可以根據不同的需求來設計出對應的共振頻率。裂環共振器的工作原理是透過外加的磁場產生電磁感應激發出共振模態。裂環共振器從二十世紀初發展至今已經是相當成熟了，從微波到紅外線都有所應用，像是我們常見的濾波器、吸收器。 由於無線通訊快速發展，訊號傳輸的速度越來越快並需要將不同系統傳輸過來的訊號整合在一起，過去影響不大的問題隨著通訊技術的快速發展逐漸明顯的干擾到元件或是系統整體的表現。濾波器因此越來越被重視，對於濾波器的要求也越來越嚴格。 本研究打算將目前只在模擬成功階段的可同時濾除Wifi 2.4GHz及Wifi 5GHz頻段訊號的用雙裂環共振器設計成的濾波器做實際的實驗。但由於實驗儀器本身的限制，因此將雙裂環共振器的作用頻段減為原本的1/3，也就是0.8GHz ~ 0.83GHz以及1.71GHz ~ 1.95GHz。並且我們發現，使用兩大兩小的結構相較於四個小的結構的雙裂環共振器串接在一起，在1.71GHz ~ 1.95GHz的頻段附近無論是-10dB還是-15dB頻寬都要來的寬。此外，我們成功將在0.8GHz ~ 0.83GHz以及1.71GHz ~ 1.95GHz所做的模擬結果實際實驗出來，並且與模擬的結果相差不大。

A split-ring resonator can be viewed as an LC circuit and can be designed to resonate at a specific frequency according to different requirements. The working principle of a split-ring resonator involves exciting resonance modes through an externally applied magnetic field. Split-ring resonators have matured considerably since the early twentieth century and have found applications ranging from microwaves to infrared, such as in common filters and absorbers. With the rapid development of wireless communication, signal transmission speeds are increasing, and there is a need to integrate signals from different systems. Issues that previously had little impact are now gradually interfering with the performance of components or entire systems due to the rapid advancement in communication technology. Consequently, filters are becoming increasingly important, and the requirements for filters are becoming stricter. In this study, we intend to experimentally validate a dual split-ring resonator designed as a filter that can simultaneously accommodate the Wi-Fi 2.4GHz and Wi-Fi 5GHz frequency bands, which has only been successfully simulated thus far. However, due to limitations of the experimental instrumentation, the operating frequency range of the dual split-ring resonator is reduced to one-third of the original, namely 0.8GHz to 0.83GHz and 1.71GHz to 1.95GHz. Additionally, we observed that using a configuration of two large and two small split-ring resonators connected together results in a wider-10dB or -15dB bandwidth near the 1.71GHz to 1.95GHz frequency range compared to using four small split-ring resonators. Furthermore, we successfully conducted experiments to validate the simulated results obtained at 0.8GHz to 0.83GHz and 1.71GHz to 1.95GHz, with the experimental results closely matching the simulated ones.