Let's talk about some basic concepts in electromagnetic wave propagation.

讓我們來談談電磁波傳播的一些基本概念。

It can help you understand some of the phenomena we might encounter when working with antennas.

它可以幫助你理解我們在使用天線時可能遇到的一些現象。

The first fundamental concept is the Huygens principle.

第一個基本概念是惠更斯原理。

It simply states that every point on a wavefront can be considered as a source of new spherical waves.

它簡單地指出，波陣面上的每一點都可以被視為新球面波的來源。

The envelope of these waves become new wavefronts.

這些波的包絡線成為新的波面。

This is particularly useful when explaining our next concept, diffraction.

這在解釋下一個概念--衍射時尤其有用。

Diffraction is the bending of waves around obstacles or the spreading of waves when they pass through narrow openings.

衍射是指波浪在障礙物周圍發生彎曲，或者波浪在通過狹窄開口時發生擴散。

Using the Huygens principle can be visualized like this.

利用惠更斯原理可以這樣直觀地理解。

When a wave enters an opening, it becomes a new source of spherical waves, and it seems like the original wave was spread out.

當波浪進入一個開口時，它就會成為一個新的球形波源，看起來就像原來的波浪被散開了。

Diffraction is best observed when the size of the opening is comparable to the wavelength of the wave.

當開口的大小與波長相當時，最容易觀察到衍射。

When we make the opening larger, the effect is still there, but much less dominant.

當我們把開口變大時，效果依然存在，但主導性大大降低。

Let's move on to absorption.

讓我們繼續討論吸收問題。

Absorption occurs when the energy of an electromagnetic wave is taken up by the material the wave is passing through.

當電磁波的能量被電磁波通過的材料吸收時，就會發生吸收。

The electromagnetic wave interacts with the atoms in the material, and their energy is converted into other forms, typically heat.

電磁波與材料中的原子相互作用，其能量被轉化為其他形式，通常是熱能。

In general, as the frequency of the wave increases, so does the absorption.

一般來說，隨著波的頻率增加，吸收也會增加。

Also, different materials have varying degrees of absorption, so the choice of material depends on the application.

此外，不同的材料具有不同程度的吸收性，是以材料的選擇取決於應用。

When selecting materials for pigtails and ray domes, we aim for the lowest absorption.

在選擇尾纖和射線圓頂的材料時，我們的目標是降低吸收率。

While for RF absorbers used in anechoic chambers, we aim for the highest.

對於在消聲室中使用的射頻吸收器，我們的目標是達到最高。

Any transition between materials causes at least some of the electromagnetic energy to reflect.

材料之間的任何過渡都會導致至少部分電磁能發生反射。

The law of reflection states that the angle in which the wave hits the boundary is equal to the angle at which it is reflected.

反射定律指出，波擊中邊界的角度等於波被反射的角度。

This may be desired when designing antennas such as parabolic dishes, or it can be a cause of great concern when designing a ray dome where the signal reflected back into the antenna should be as low as possible.

這可能是設計拋物面天線等天線時所希望的，也可能是設計射線穹頂時非常擔心的問題，因為在設計射線穹頂時，反射回天線的信號應儘可能低。

So these were some basics of wave propagation.

以上就是有關波傳播的一些基本知識。

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