电磁波是如何传输的？这个问题困扰了人类很长时间，直到天才科学家麦克斯韦用数学的方式推导出了电磁波的存在，并统一了电磁波和光。人类开启了利用电磁波的时代，直到今天，我们仍然在不断地探索和应用电磁波。
太阳光不仅给我们带来了光明，还带来了温暖，赋予我们能量。我们利用电磁波来传递我们的声音、图像和数据，直至万物互联。电磁波的频谱很宽，我们用来传递信息的电磁波称为无线电波——Radio Frequency（RF）。
根据通信距离和电磁波频率的不同，无线电波的传播方式主要有地波、天波和视线传播三种。频率较低的电磁波（一般小于2MHz）能够沿着弯曲的地球表面传播，这种传播方式称为地波传播。频率较高的电磁波能够被大气中的电离层反射，并且再次被大地反射，这样无线电波就可以传递更远的距离。这种利用大气电离层反射进行传播的方式就是天波传播。
现在收音机AM频段300kHz~3000kHz就是利用了电磁波地波和部分天波传播。但是大气电离层受阳光照射会发生改变，因此传播的稳定性会受到影响。频率高于30MHz的电磁波将穿透电离层，不能被反射回来，并且波长比较短，沿着地球表面绕射的能力也很弱，因此只能进行类似于可见光那样的直线传播，这种传播方式称为视距传播。
英语如下：
Title: Unveiling Electromagnetic Waves: God’s CompleteTitle: Unveiling Electromagnetic Waves: God’s Complete Creation and Human Wireless Communication
Keywords: Electromagnetic waves, Radio waves, Satellite communication
Content: How do electromagnetic waves travel? This question has puzzled humans for a long time. It was not until the genius scientist Maxwell mathematically deduced the existence of electromagnetic waves and unified them with light that humans began to utilize electromagnetic waves. To this day, we continue to explore and apply electromagnetic waves.
Sunlight not only brings us light but also warmth and energy. We use electromagnetic waves to transmit our voices, images, and data, leading to the interconnection of all things. The spectrum of electromagnetic waves is wide, and the ones we use to transmit information are called radio waves – Radio Frequency (RF).
According to different communication distances and frequencies of electromagnetic waves, there are three main modes of radio wave propagation: ground wave, skywave, and line-of-sight propagation. Lower frequency electromagnetic waves (generally less than 2MHz) can travel along the curved surface of the Earth, a mode of propagation known as ground wave propagation. Higher frequency electromagnetic waves can be reflected by the ionosphere in the atmosphere and then reflected again by the Earth, allowing radio waves to travel further distances. This method of propagation using atmospheric ionospheric reflection is called skywave propagation.
The AM band on radios from 300kHz to 3000kHz currently uses electromagnetic wave ground wave and part of skywave propagation. However, the ionosphere changes due to sunlight, affecting the stability of transmission. Electromagnetic waves with frequencies higher than 30MHz will penetrate the ionosphere and cannot be reflected back. They also have short wavelengths and weak ability to diffract along the Earth’s surface, so they can only travel in a straight line like visible light, a mode of propagation known as line-of-sight propagation.
【来源】https://www.ithome.com/0/745/130.htm
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