Which antenna is more suitable for you to expand the wireless network
Introduction
In most cases, the most direct way to expand the coverage of a wireless network is to replace the high-gain antenna or install an external antenna, preferably an omnidirectional or directional antenna.
Directional antennas Directional antennas are usually used in point-to-point systems and sometimes used at far-end points in point-to-multipoint systems. If you want to connect two different locations, this antenna is recommended. Directional antennas mainly include: backfire antennas, flat antennas, Yagi antennas, parabolic antennas, etc.
Omnidirectional antenna This kind of antenna is usually used in the point-to-multipoint system used in the center of the network, or used in your car. The omnidirectional antenna serves as the central antenna to provide signals to other computers or devices (such as wireless printers, PDAs, etc.). You can also use 2 omnidirectional antennas to build a point-to-point system. Usually we do not recommend you to do this because the signal is not concentrated and the effect is very poor. Commonly used omnidirectional antennas are: vertical omnidirectional, ceiling antenna, rubber duckbill antenna, desktop antenna and mobile vertical antenna.
Point-to-point Point-to-point usually includes 2 different wireless APs, or a building-to-building wireless connection. But there are exceptions. If your AP is crossing a river or valley, you want to provide wireless access to multiple users. This is a point-to-multipoint method, but you need to use a directional antenna.
Point-to-multipoint Point-to-multipoint usually shares a WLAN, or family members share the Internet connection, or share the Internet connection with neighbors. It can also be WAP (Wireless Access Points) such as coffee shops, train stations, and airports.
Signal coverage The signal coverage includes several main factors, including the output power of the wireless network card or router, the signal receiving sensitivity of the wireless network card, and the situation of obstacles on the transmission path, such as trees and walls. Because there are so many factors affecting your coverage, it is impossible to say very clearly here. But a common method is to choose a suitable antenna. Why do you say that? Because the output power is very small.
The output power of most wireless network cards is 32mw (+ 15dBm), which is similar to the power consumption of a high-power LED. The LED is luminous, and it can be seen by buildings at long distances or through trees. Why is the output power so small? Because the working frequency of 802.11 is the same as microwave oven, it is 2.4 GHz.
Antenna for specific environment
One of the questions we often ask is how to choose a suitable antenna for a specific environment. This is a simple and complex problem, depending on the user's special needs, that is, what they want to do. The current 802.11b (11 Mbps), 802.11g (54 Mbps) and SuperG (108 Mbps) standards provide a relatively good speed. The signal effect mainly depends on the signal strength and noise of your wireless network card and wireless router. In other words: the greater the signal strength and the lower the noise, the better the signal.
There are many kinds of wireless applications, in the home, office, etc. Let us look at these applications.
Family Antennas for home use are the easiest to buy, and the easiest to select and install. In most cases, you only need to use the antenna on the remote computer. We recommend that you use an antenna on a remote computer, because when you install it on a router, the signal will expand to your neighbors, and safety will not be guaranteed. If you have multiple study rooms or a relatively large house, you need to install an antenna on each computer so that the range and bandwidth can be improved. Every wall you need to pass through will reduce the signal strength. In order to achieve stronger signal strength and signal, we recommend installing a 5db antenna, desktop antenna, etc. on the remote PC. The best way is to use an antenna to test on the remote PC.
Office Office antennas are generally required to be beautiful. If you want to be able to access the network while working anywhere in the office without using a network cable, then you must first buy a good quality wireless network card, and then install an antenna on the wireless router to maximize the signal extension. It's very simple. However, if your office is divided into several different rooms or very large, there will be some difficulties.
Regarding the dual antennas, aside from the environmental factors, under the condition that the transmission power is fixed, the dual antennas can effectively increase the wireless coverage, and on average bring about a 3dB signal to noise ratio gain (referring to the ratio of useful signal power to useless power) Currently, the gain of wireless routing antennas on the market is generally 2dBi, but this does not mean that the two antennas are 4dBi. The dual antenna is not simply 1 + 1 = 2, but the automatic coordination of the two antennas, also known as antenna diversity. The antenna is only received, and the other one is received and sent again. The router can continue to choose the antenna with better reception to receive wireless signals, so as to achieve the desired effect.
Why is an antenna in motion using a wireless network in the car? This problem is very good. Now in some places in developed countries abroad, wireless services are provided throughout the city, and you can directly access the Internet in the car. WiMAX networks are developing in this direction. In the near future, some major cities in China will also provide high-quality wireless access services.
Yagi antenna Yagi antenna is designed by two Japanese people. Originally designed for radio equipment, it is now also used in 802.11 equipment. These antennas are relatively directional, and are usually used in point-to-point systems or point-to-multipoint remote points. For outdoor use, consider using a waterproof Yagi antenna. This antenna has good signal strength and can be achieved in some environments A few kilometers of transmission!
Backfire antenna The backfire antenna is a small directional antenna with high gain. This antenna looks like a round dish. This antenna is recommended for point-to-point or point-to-multipoint systems. The backfire antenna has a gain of 16dbi and a diameter not exceeding 30cm.
Parabolic antenna This is a true high-power antenna, much like a "pot" for receiving satellite signals. The gain is very large, but there are certain difficulties in aligning the target direction. The greater the gain of the antenna, the narrower the beam and the stronger the directivity, so the more difficult it is to adjust. This kind of antenna is usually used in long-distance point-to-point systems. When this antenna works, it concentrates the power to a central point, and concentrates the wireless signal to a specific area, just like an open flashlight.
When choosing the antenna gain, the issues you need to consider The antenna gain you need depends on the obstacles on the transmission path, the range you need to cover and the performance of your wireless network card. When choosing an antenna, these factors must be taken into account. For ordinary consumers, the antenna gains of wireless routers and APs currently on the market are between 2dBi, 3dBi and 5dBi, which can fully meet the daily environment. For users with special needs, there are 8dBi and 9dBi antennas. Can be replaced by the user.
About signal interference Like all wireless devices, WIFI also has the problem of interference. Just like when you are listening to the radio, sometimes you can hear some noise. This is interference. The same thing will happen in the WIFI system, but it is not so obvious. Mainly affecting the WIFI system are microwave ovens, some specific lighting systems, other 802.11 equipment, microwave transmission equipment, and even the high-speed processor of the computer can cause interference of the 802.11 system. When you use wireless devices, these factors must be considered.
Summary: The most important thing for a wireless network is speed and signal effect. The original equipment may not meet our actual requirements. This requires the help of installing an antenna. You can choose the most suitable one according to the actual situation.
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