Microwave antennas form the core of many modern communication networks. They are the tools that allow us to use wireless devices and even track weather patterns. It may seem like something that important should be complicated, but they are actually fairly simple.
Transmission and Reception
An antenns is essentially a length of metal wire that attaches to a radio to help it send and receive signals. Those take the form of microwaves, which are a type of electromagnetic wave.
The microwaves can pass through the air very quickly, and the systems use them to carry information. The transmitter converts the information that it needs to transfer into a specific wave, which it then broadcasts through the air. The wave will eventually reach another antenna, which receives the wave and converts it to an electrical signal, which the rest of the radio can process. The radio then turns it back into the information that a human can understand.
There are a few different ways for an antenna to send or receive a signal. The easiest way is through a line of sight system, where the wave goes in a straight line to reach the receiver. That has limited range and physical objects can block it, which is why communication companies either use a large network of antennas or alternative methods. Ground waves are also an option for short and moderate distances. They follow the curve of the planet, which makes it possible for them to go past the horizon. Transmitters can even aim their waves upwards and bounce them off of the atmosphere to send them over long distances and get around obstacles. That works best at night, and is why it is easiest to pick up distant radio stations late in the day.
All of those methods have limited range or can run into trouble with obstructions. Even signals that ultimately get through can still suffer a loss of quality if they travel over long distances or through areas with bad conditions. The best solution to that problem is to build a network of antennas that can send signals to each other. The antennas work just like any others, in that they encode data as a wave, send it, receive it, and decode it. The difference is that some of the antennas will send the data back out as a new wave to make sure it can reach tis destination.
Breaking the journey up into a bunch of small steps makes it easier to avoid problems and helps to avoid degradation of the signal. It does increase the cost of infrastructure, but communications are so important that the increased cost is an acceptable price for increased reliability and clarity.