What is the difference between the wireless router's antenna?

A friend asked the router to select a few antennas. Before choosing a router to buy several antennas, we must first understand the difference between the one, two, and three antennas of the wireless router.

For older wireless routers up to 11g, an antenna supports up to 54Mbps.

For an old-fashioned wireless router up to 11n protocol, an antenna supports up to 150Mbps;

For new wireless routers up to 11ac, an antenna supports up to 433 Mbps;

If you hear how fast a router can claim to be, you can quickly see that it has several antennas. There are mainly the following types of wireless routers on the market today:

"Both" 54Mbps, 150M is definitely an antenna;

"Both" 300Mbps is two antennas (two 11n)

"Both" 450Mbps is three antennas (three 11n)

"Both" 900Mbps is four antennas (three 11n+one 11ac)

"The so-called" 1300Mbps is five antennas (three 11n + two 11ac)

"Both" 1750Mbps is six antennas (three 11n+three 11ac)

If this is not the case, then only that router uses the "built-in antenna" or "false antenna."

On the contrary, if you only see the router with several antennas, it is difficult to know the maximum rate of support for this product without looking at the specifications. However, dual antennas are at least 300M, three antennas are at least 450M, and four antennas are at least 900M...

Five antenna router:

Six-antenna router:

I know you will ask: "Why is the higher the antenna, the higher the rate?"

It would have to lead to the concept of MIMO. The idea of ​​the multiple input multiple output (MIMO) technology is to install multiple antennas at the transmitting end and the receiving end at the same time. The transmitter uses multiple antennas to send signals simultaneously, and the receiver also has multiple antennas to receive signals, enabling more information to be transmitted in the same frequency domain and time domain. It can double the system channel capacity without increasing the spectrum resources and antenna transmit power.

How do you do it? Here we give an example:

In a small, very quiet room, two couples are talking. When Nyima said, "You are scarce to you," Nyima's girlfriend and Tynema's girlfriend can hear clearly. In other words, in this environment, the amount of information received by the listener at the same time is twice as much as SISO (one-to-one whispering).

Now we change the environment. Suppose the two couples are chatting in a very noisy little bar (or the two parties are far away from each other). Although Wang Nima raised his voice and said, "You are scarce," his "female" friends could not hear clearly.

Then, if Wang Nima and Ting Nima shout at the same time, "You are scarce to you?" Although the amount of information has not increased, the opportunity for listeners to hear clearly is much greater because the two signals transmit the same information. If Nyima's girlfriend couldn't hear Wang Nima's "You are scarce to you", you could hear Din Nima's "You are rare." Who says it? The key is that the information is transmitted and the communication is successful! From the communication point of view, this is called improving the reliability of communications.

This is how MIMO works.

MIMO has two modes: spatial multiplexing and transmit/receive diversity.

Spatial multiplexing means that the data to be transmitted can be divided into several data streams and then transmitted on different antennas so as to increase the transmission rate of the system.

You can think of Nyima, Tynima, and many other Nima as the antenna of the router, and treat the Nyima girlfriend, the Dinami girlfriend, and other Nyima girlfriends as receiving devices (for example, notebooks). Antenna for mobile phones, PADs, etc.) It is easy to figure out the relationship between multiple antennas and speed.