An antenna is a device that transmits and receives electromagnetic waves.

天線是一種發射和接收電磁波的裝置。

It's an interface between a wave traveling in a cable and flying through the air.

它是在電纜中傳播的波與在空中飛行的波之間的界面。

It's also important to understand that antennas work in both directions.

同樣重要的是要了解天線是雙向工作的。

You can't have an antenna that only receives or only transmits.

天線不能只接收或只發射信號。

Electromagnetic waves have an electrical and a magnetic component.

電磁波包含電波和磁波。

Two basic properties of a wave are frequency and wavelength.

波的兩個基本特性是頻率和波長。

Frequency says how many times a wave repeats its shape per second.

頻率表示波形每秒重複的次數。

Wavelength is the distance over which the wave repeats a shape.

波長是波形重複的距離。

For example at 10 gigahertz the wavelength is roughly 30 millimeters long.

例如，10 千兆赫的波長大約為 30 毫米長。

At 5 gigahertz it's roughly 60 millimeters long and at 2.4 gigahertz it's roughly 120 millimeters long and so on.

頻率為 5 千兆赫時，長度約為 60 毫米，頻率為 2.4 千兆赫時，長度約為 120 毫米，以此類推。

So how does an antenna work?

那麼，天線是如何工作的呢？

In order to explain that we need to break it down into the two most common types of antenna categories.

為了解釋這一點，我們需要將其分為兩種最常見的天線類型。

Resonant and Aperture Antennas, as the name suggests, function on the principle of resonance.

諧振和孔徑天線，顧名思義，是根據諧振原理髮揮作用的。

When an antenna resonates it radiates the signal that's fed to it.

當天線產生共鳴時，就會輻射出饋送給它的信號。

The simplest example of a resonant antenna is a wire or a dipole.

諧振腔天線最簡單的例子就是導線或偶極子。

The length of the dipole has to be equal to at least half of the signal wavelength in order for it to work.

偶極子的長度必須至少等於信號波長的一半，這樣才能發揮作用。

This means that the radiation properties and bandwidth, which is usually quite narrow, depend on the size of the antenna.

這意味著輻射特性和帶寬（通常很窄）取決於天線的尺寸。

Some examples of antennas based on resonant elements are patches, loops, and yaggies.

基於諧振元件的天線有貼片天線、環形天線和矢狀天線。

Aperture antennas radiate electromagnetic waves through an opening.

孔徑天線通過一個開口輻射電磁波。

An example of Aperture antennas would be a horn.

號角就是孔徑天線的一個例子。

The radiation diagram of an Aperture antenna depends on the size and the shape of the Aperture, but their bandwidth of operation depends on the size and the shape of the feeding structure.

孔徑天線的輻射圖取決於孔徑的大小和形狀，但其工作帶寬則取決於饋電結構的大小和形狀。

This is why the radiation properties and performance of horn antennas are very stable over a very wide band.

這就是為什麼喇叭天線的輻射特性和性能在很寬的頻帶內非常穩定。

The main parameters of an antenna are the frequency range, the shape of its radiation pattern, and its gain.

天線的主要參數包括頻率範圍、輻射模式形狀和增益。

So we'll talk about some of these topics in our next video.

是以，我們將在下一個視頻中討論其中的一些話題。