Analysis of common types of antennas

     Since wireless networks use radio waves to transmit data signals, using radio frequency (RF) technology to send and receive data through the air, the role of the antenna is extremely important. With the popularity of WLAN, there are many people who are looking for antennas that can expand the coverage of wireless signals, taking you through the types of antennas.

     In most cases, the most direct way to extend the coverage of a wireless network is to replace the antenna with a high gain antenna or to install an external antenna, preferably an omnidirectional or directional antenna.

Directional Antennas

     Directional antennas are usually used in point-to-point systems, and sometimes at the far end of a point-to-multipoint system, and are recommended if you want to connect two different locations. The main types of directional antennas are: back-firing antennas, flat antennas, Yagi antennas, parabolic antennas, etc.

Omni-directional antenna　　

     This type of antenna is usually used in networks where the center point is used in a point-to-multipoint system, or in your car. Omni-directional antennas act as a center antenna to provide signals to other computers or devices (e.g. wireless printers, PDAs, etc.). You can also use 2 omni-directional antennas to set up a point-to-point system, which we usually do not recommend because the signal is not centralized and the results are very poor. Commonly used omni-directional antennas are: vertical omni-directional, ceiling antenna, rubber duckbill antenna, desktop antenna and mobile vertical antenna.

Point-to-Point　　

    Point-to-point usually consists of 2 different wireless APs, or a building-to-building wireless connection. There are exceptions to this, if your AP is crossing a river or valley and you want to give wireless access to multiple users, this is the point to multipoint approach, but with directional antennas.

Point-to-Multipoint　　

     Point-to-multipoint is usually sharing a WLAN, or a family member sharing an Internet connection, or sharing an Internet connection with a neighbor. It can also be WAP (Wireless Access Points) in coffee shops, train stations, airports etc.

Signal Coverage　　

     Signal coverage consists of several major factors, including the output power of the wireless card or router, the sensitivity of the wireless card's signal reception, and the presence of obstacles in the transmission path, such as trees, walls, etc. With so many factors affecting your coverage, it's impossible to be very clear here. But a common method is to choose a suitable antenna, why? Because the output power is very small.

     The output power of most wireless cards is 32mw (+15dBm), which is about the same power consumption as a high-power LED, which is illuminated so that it can be seen from a distance, or through trees and buildings. Why is the output power so low? Because 802.11 operates on the same 2.4 GHz frequency as a microwave oven.

Antennas for Specific Environments　　

     One of the questions we are often asked is how to choose a suitable antenna for a specific environment. This is both a simple and complex question, depending on the particular needs of the user, i.e. what they want to do. The current 802.11b (11 Mbps), 802.11g (54 Mbps) and SuperG (108 Mbps) standards offer a relatively good speed, and the signaling effect depends largely on the signal strength and noise of your wireless 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 applications for wireless, in the home, in the office, etc. Let's look at some of these applications.

Home　

     Antennas for home use are the easiest to purchase and the simplest to select and install. In most cases, it is only necessary to use the antenna on the computer at the remote end. We recommend that you use the antenna on the computer at the far end, since when you install it on your router, the signal expands to your neighbors and security is not guaranteed. If you have more than one den or a larger house, you will need to install antennas on each computer so that range and bandwidth can be improved. Each wall you need to go through reduces the strength of the signal. To achieve greater signal strength and signal, we recommend installing a 5db antenna, desktop antenna, etc. on the far end PC. The best way to test this is to start with an antenna on a PC at the far end.

Office　　

    Antennas for offices are generally required to be beautiful and aesthetically pleasing. If you want to be able to access the internet while working anywhere in the office without using a cable, then first you have to buy a good quality wireless card and then install an antenna on your wireless router in order to extend the signal to the maximum. It is quite simple. However, if your office is divided into several different rooms or is very large, there will be some difficulties.

About dual antennas　　

   Putting aside the influence of environmental factors, in the case of a certain amount of transmit power, dual antennas can effectively increase wireless coverage, bringing about 3dB signal-to-noise ratio gain on average (which is the ratio of useful signal power to useless power), the antenna gain of wireless routing antennas on the market is generally 2dBi, but this does not mean that two antennas are 4dBi, dual antennas are not simply 1+1=2, but two antennas Dual antenna is not simply 1+1=2, but two antennas are automatically coordinated, also known as antenna diversity, one antenna only receives, the other receives and sends, the router can constantly go to select the antenna that receives better to receive wireless signals, so as to achieve the desired results.

Antennas on the move　　

     Why should I use wireless network in my car? This question is very good, now in some foreign developed countries, the whole city has provided wireless services, in the car you can directly access to the Internet. WiMAX network is developing in this direction, the near future, some of the country's major cities will also provide high-quality wireless access services.

Yagi antenna　　

     Yagi antenna is designed by two Japanese. Initially designed for radio equipment, now also used in 802.11 equipment. These antennas are more directional and are usually used in point-to-point systems or point-to-multipoint remote points. To use them outdoors, consider using a waterproof Yagi antenna, which has good signal strength and can reach several kilometers of transmission in some environments!

Back-firing Antennas　　

     A back-firing antenna is a small directional antenna with relatively high gain. This antenna looks like a disk and this antenna is recommended for use in point-to-point or point-to-multipoint systems. Back-firing antennas have a gain of 16dbi and a diameter of no more than 30cm.

Parabolic Antenna　　

     This is a really high power antenna, much like a “pot” that receives satellite signals, with a very large gain, however, there is some difficulty in aligning the direction of the target. The greater the gain of the antenna, the narrower and more directional the beam, so the more difficult it is to adjust. This type of antenna is usually used in long-range point-to-point systems. This type of antenna works by concentrating the power to a central point and focusing the wireless signal to a specific area, like an open flashlight.

Things to consider when choosing antenna gain

     The gain you need from your antenna depends on the condition of obstacles in the transmission path, the range you need to cover and the performance of your wireless card. All of these factors need to be taken into account when choosing an antenna. For ordinary consumers, the antenna gains of wireless routers and APs currently on the market range between 2dBi, 3dBi and 5dBi, which are perfectly suited for everyday environments, and there are also 8dBi and 9dBi antennas available for users with special needs to replace them.

About signal interference

     Like all wireless devices, WIFI also has the problem of interference. Just like when you listen to the radio, sometimes you can hear some noise, this is interference. The same thing happens in a WIFI system, just not as noticeable. The main things that affect WIFI systems are microwave ovens, some specific lighting systems, other 802.11 devices, microwave transmission devices, and even high speed processors in computers can cause interference in 802.11 systems. All of these factors should be taken into consideration when you are using wireless devices.

　　Summary: The most important thing about wireless network is the speed and signal effect, the original equipment may not be able to meet our actual requirements, which requires the help of additional antennas, you can choose the most suitable one according to the actual situation.