此篇論文介紹利用週期性結構的高反射特性，來設計位於W頻帶(75~　110 GHz)的低損耗率的矩形波導管，此週期性結構由高折射率的介電質與低折射率的介電質交互週期排列，其每一層介電質的厚度由破壞性干涉的原理來決定，此結構將可看見周期性的高反射率頻帶，在此頻帶內反射率將趨近於一，利用此特性來設計波導管，可以得到損耗率低於任何金屬波導管。另外我們亦會討論金屬波導管耦合進入Bragg waveguide的效率，以及利用時域分析討論TE01模的穿透。

We investigate the transmission loss of the rectangular waveguide mode (TE01) at W-band with a Bragg structured sidewall. To design and fabricate the Bragg sidewall, we first study the propagation properties of a periodic multilayer structure, each layer consisting of a high refractive index and a low refractive index dielectric material. The thicknesses of dielectric materials are properly designed to form the destructive interference at the operating region. The periodic bandgap is observed with the reflection coefficient close to unity at the stop band. This Bragg sidewall can perfectly confine the energy in the rectangular waveguide with extremely low attenuation much lower than any metallic wave guide.

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