新型微波縮小化地面電流扼流結構及其應用

Abstract

本論文中展示了一種新型微波縮小化地面電流扼流結構，利用LC並聯諧振原理，將工作頻率設計操作在5.25GHz之印刷式結構。在雙面金屬面之FR4基板上，其中一金屬接地面蝕刻出曲折型槽孔(Meander-type Slot)，另一面金屬面蝕刻出長方型金屬線，並藉由貫穿導通孔(Through Hole Via)接通，其整體結構提供電感性和電容性效應藉以產生一諧振頻率，形成類似開路結構(Open-like)高阻抗被動元件。另為方便分析微波縮小化地面電流扼流結構各項結構參數及其等效電路在其章節後提出一測試結構幫助驗證。 接著介紹兩種利用此結構之應用。應用一：減少行進波在接地層之效應：由傳統倒L型單極參考天線應用結構切入說明，因為系統接地層的存在使得倒L型單極天線的輻射場會往接地層的方向偏，大幅降低高頻電路之電磁相容性(EMC)及增加電磁干擾(EMI)。經由導入接地面電流扼流結構後倒L型單極天線的輻射場方向可明顯改變進而提高電磁相容性及降低電磁干擾。應用二：增加天線間隔離度：因系統小型化及多根天線應用趨勢，天線間耦合影響會越嚴重，發射的訊號透過天線耦合回授到系統電路□面干擾高頻電路特性。經由導入接地面電流扼流結構後，可增加天線間隔離度。印刷方式可降低成本，易製作，縮小化可不佔空間，在無線通訊系統應用上可提供多項優勢。

In this paper present a new microwave miniaturized ground-plane current choke. The first one that we will introduce the structure of the choke frequency operated at 5.25GHz.The designed theory follows induc- tance and capacitance parallel resonance. It be composed of a meandered slot pattern etched on the ground plane, a metal rectangle trace on the upper one for FR4 substrate,through them by a via.The overall structure provide the characteristic of the inductance and capactiance generated a resonance frequency and be formed similarly open-like high impedance passive component. In order to easily analyze every parameter of the printed current choke and the equivalent circuit, this proposed a test structure to verify behind the chapter. Continue we will introduce two applications. One application, “reducing the traveling wave effect on the ground plane”: It accounted by conventional inverted-L monopole antenna structure. Because of the ground plane existed, resulted in tipped radiation pattern toward the groundside. It degraded the electromagnetic compatibility (EMC) and rose in electromagnetic interference (EMI) of the high frequency circuits. It clearly changed the direction of the antenna radiation pattern and enhanced the electromagnetic compatibility when ground plane current choke add in. Another application,”increasing the isolation between antenna elements”: The current trend is system miniaturized and many antennas application. It is becoming more and more serious for antenna coupling. The transmitted signal come back into system and interfered the characteristic of the high frequency circuits. It increased isolation between antennas when ground plane current choke add in. The proposed ground-plane ground plane current choke has printed profile, low cost, and ease to fabcriate. It has the advantage of the wireless communication application.