印刷式超寬頻天線

Abstract

本論文提出兩種新穎的平面印刷式超寬頻天線(Ultra-Wideband Antenna, UWB Antenna)，其頻率操作在3GHz ~ 10GHz。此兩種天線的結構分別為火山型(Volcano Smoke)及梯形的形狀。他們的結構都是建立於印刷式單極天線的基礎。他們兩者都具有寬頻的特性、全方向性的場型及易於製作。論文中亦致力於此兩種形式的天線的最小化及最佳化。 最後，利用既有的資訊，嚐試將單一導體帶狀天線設計於UWB的操作頻率範圍內。但由於其第一高階模在低頻的特性不如高頻的好，且饋入的結構所能激發的頻寬有限。因此我們將單一導體帶狀漏波天線頻段設計於3.9GHz ~ 8.64GHz，相對的頻寬約2.22:1，仍為一寬頻天線。因其正歸化相位常數從最低點0.94變化至1非常的緩慢且近似於1，所以單一導體帶狀漏波天線在endfire的方向有幾近固定的主波束。

Two novel ultra-wideband (UWB) planar printed antennas that operate from 3GHz to 10GHz are proposed in this thesis. The configuration of these two antennas are volcano smoke and trapezoidal shapes. The structures of the two antennas are based on the planar printed monopole antenna. Both of them have wideband characteristic, omni-directional pattern and ease of construction. Minimization and optimum of the two antennas are developed in our research. Finally, we try to design the single-conductor strip antenna that operates at the frequency range of the UWB systems. The characteristic of the first higher order leaky-mode at lower frequency is not as good as that at higher frequency and the bandwidth that is excited by the broadband feeding structure is limited. We will design a single-conductor strip antenna that has a bandwidth of 2.22:1 (from 3.9GHz to 8.64GHz) for a VSWR 2. Because the normalized phase constant varies very small and close to 1, this single-conductor strip leaky-wave antenna has a nearly fixed mainbeam radiation pattern in the endfire direction.