Is it faster with 2 antennas or 4 antennas? I believe there must be many friends who are swaying around because of the “antenna” problem when choosing a router, and they can’t make up their minds. Let’s take Huawei Router A1 as an example, let’s talk about those things between the chat line and the router!

 

Which is faster, internal antenna or external antenna?

To answer this question, you might as well take a look at the status quo and differences between external antennas and internal antennas: external antennas appeared earlier than internal antennas. Early wireless router antennas were basically external; in recent years, internal antennas It has become popular, and all mainstream manufacturers have introduced routers with built-in antennas. Due to the built-in antenna, the appearance of the router is more fashionable and concise, and it is more in line with the aesthetics of modern people.

 

The angle of the external antenna can be adjusted, and the different placement of the antenna has a greater impact on the performance and network speed of the router. If the angle is not placed properly, it will affect the user’s Internet experience; and the built-in antenna is designed to be optimized by default. No need for user adjustment.

 

External antennas are easier to implement. If you encounter complex scenarios and environments, there are more solutions; built-in antennas must take into account the optimal space and antenna performance, which is relatively difficult to implement and requires manufacturers to have higher capabilities.

 

In fact, the internal and external antennas are just a solution to the router antenna design. Under current technical conditions, the router will not simply differ due to the internal or external antennas and the signal. Therefore, whether the external antenna or the internal antenna should not be the primary consideration when choosing a router.

 

What is the relationship between the wireless protocol and the number of antennas?

When choosing a router, users should pay more attention to the wireless protocol and the number of antennas, because they directly determine the Wi-Fi transmission rate.

 

Through official promotional materials, you can basically calculate the Wi-Fi rate of Huawei Router A1.

11ac 2*2 in the data indicates that it supports 802.11ac and 2 antennas, so the Wi-Fi rate is 433.3*2=866.6. 11n 2*2 indicates that it supports 802.11n and 2 antennas, so the Wi-Fi rate is 150*2 =300. The total of the two is 1167.6 (Gigabit), rounded to about 1200Mbps. The “Gigabit WiFi”, “Gigabit wireless router”, and “11AC technology” promoted by Huawei refer to this.

 

If you master the relationship between the wireless protocol and the number of antennas, you can easily avoid the various “pits” of the merchants when choosing a router in the future. For example, if a router claims to support Gigabit, it must support 11ac. If it does not support 11ac, it is definitely false propaganda! Another example is the number of router antennas (assuming 4), but only the highest rate of 300Mbps, which means that it actually only needs 2 11n antennas (2*150=300), and the extra two antennas are very likely It’s just a display, used to bluff people and increase their worth!

 

Should the router choose a product with a relatively high price and configuration?

Whether it is necessary to buy a higher-end wireless router depends on the cost performance of the product and the actual needs of users. The main consideration here is the home broadband and the size of the apartment. At present, the home broadband in most areas in China is 100M and below, and you can choose a dual-band route of 1200M. If the home broadband is greater than 100M, you need to choose dual Gigabit routers, such as Huawei Router A1 Enjoy Edition, can give full play to every megabit speed of ultra-100M fiber. Of course, if it is a large apartment with an area of ​​more than 120 square meters, multiple routers need to be used for intelligent networking to achieve seamless Wi-Fi coverage throughout the house.

 

Knowing yourself and the enemy can survive all battles. I believe that after understanding the relationship between routers and antennas, friends will be more calm and wise, less entangled and hesitate when buying routers in the future!

It has been almost a hundred years since the birth of the walkie-talkie, half a century before the invention of the mobile phone. But in the last century, mobile phones have evolved from the former “big brother” to today’s smart phones, and the walkie-talkie is still the same stupid, black and thick old one, and the antenna is still external. So is the external antenna of the walkie-talkie due to technical bottlenecks or deliberately?

 

The walkie-talkie uses an external antenna

First of all, walkie-talkie is a kind of radio communication equipment, and the radio that this equipment relies on has a very important indicator called “working frequency”. The working frequency of domestic mobile phones has national standards, and mobile phones generally operate between 900MHz and 1800MHz. Communicate on two frequencies, and the state stipulates that the working frequency of public walkie-talkies (ie, civilian walkie-talkies) is between 409 and 410 MHz.

 

Civil walkie-talkies have operating frequency restrictions

In order to transmit the radio signal as much energy as possible, the antenna needs to be designed to half the wavelength. The wavelength is equal to the speed of light divided by the frequency. The higher the frequency, the longer the wavelength. In other words, the wavelength of a mobile phone is more than half smaller than that of a walkie-talkie. However, when designing an antenna, it is impossible to design the antenna to be as long as the wavelength, but the longer the better.

 

Of course, mobile phone design cannot blindly pursue signal priority. After all, the current mobile phone is a necessity, and there is only one hand. The iPhone 4 started to make the appearance of the mobile phone beautiful, so many mobile phone manufacturers will put the mobile phone antenna into the body. The interior or the outer shell is integrated, which can please consumers more. After all, people are visual animals, and good-looking things can naturally sell better.

 

The stainless steel frame of the iPhone 4 is the phone antenna

In the early days of Big Brother’s era, the antenna was externally mounted. On the one hand, the priority of the mobile phone design was not as high as it is now. On the other hand, the mobile phone signal coverage at that time was not as good as it is now. The wireless signal used by the mobile cellular network works The frequency is not as high as it is now, and the signal enhancement that a larger antenna can bring is obvious, so the mobile phone antenna in the big brother era was external, or even retractable.

 

Early Mobile Phone with external antenna

The antenna design requirements of the walkie-talkie are similar to the design requirements of the early Mobile Phone. Since the use scene of the walkie-talkie does not have high requirements for the appearance of the walkie-talkie, the priority of the appearance design is lower than the priority of the antenna design. Moreover, the operating frequency of the walkie-talkie is much lower than that of the mobile phone, and a larger and longer antenna is needed to send the signal better.

  1. What is wireless network

Wireless network, as the name implies, is a way to build a network without relying on a network cable. It is mainly realized by using wireless communication technology. There are mainly two ways of implementing wireless networks (such as 4G, 3G or GPRS) through mobile communication networks and wireless local area networks (WiFi).

  1. What is wireless bridge

The wireless network bridge, as its name implies, is the bridging of wireless networks. It uses wireless transmission to build a communication bridge between two or more networks. In addition to the basic characteristics of wired network bridges, wireless network bridges work in 2.4G or 5.8G frequency bands that do not require a wireless license, so they are more convenient to deploy than other wired network equipment.

 

To understand the role of a wireless network bridge, it can be used to connect two or more independent network segments. These independent network segments are usually located in different buildings, hundreds of meters to tens of kilometers apart, and can be widely used in different buildings. The interconnection between things.

 

At the same time, according to different protocols, wireless bridges can be divided into 2.4GHz bands 802.11b, 802.11g and 802.11n, and 5.8GHz bands 802.11a and 802.11n wireless bridges.

 

  1. The meaning of wireless bridge 2.4G and 5.8G

2.4G bridge:

The advantages are low frequency, large wavelength and strong diffraction ability. Simply put, the transmission performance is good, and the transmission path is slightly blocked and it is not a big problem. Then there is the relatively low cost.

 

The disadvantage is that there are many devices that use the 2.4G frequency band, and the electromagnetic wave signals emitted by the bridge are easily interfered by signals emitted by other devices, resulting in a decrease in transmission quality. Then it is limited by the transmission bandwidth of the 2.4GHz frequency band itself, which generally does not exceed 300Mbps

 

5.8G bridge:

The advantages are high frequency, relatively pure channel, and large transmission bandwidth. The transmission bandwidth starts at 433Mbps and can easily reach more than 1Gbps. It is suitable for scenarios with high data transmission requirements.

 

The disadvantage is that the frequency is high, the signal wavelength is short, the penetration is poor, and there can be no obstruction during the propagation. The cost of 5.8G equipment is higher than that of 2.4G, and it is still in the popularization stage.

 

The wireless bridge transmission system usually consists of two or more wireless devices. Due to the two-way transmission of data, each device needs to have the ability to send and receive wireless signals.

 

  1. The working principle of wireless bridge

The working principle of a wireless network bridge is that the network bridge uses air as a medium to transmit signals. Simply put, one end of the network bridge converts the signal in the network cable into a wireless electromagnetic wave signal and directionally transmits it into the air. The role of the bridge at the other end is just the opposite. It receives wireless electromagnetic wave signals in the air and converts them into wired signals.

 

Wireless electromagnetic wave signals can be transmitted using air as the transmission medium, which can solve many difficult problems in wired deployment and construction: such as highways, rivers, mountain streams, or road hardening, wired deployment and construction difficulties.

 

Wireless bridge networking has obvious advantages. It can realize point-to-point or point-to-multipoint network connection over a distance of up to 50 kilometers, and the data transmission speed is up to 108Mbps. Effectively solve the problem of network connectivity in the interval. As long as the wireless signal coverage area, the client can easily access the network, converge the system, without any wiring, and the wireless terminal can achieve zero-configuration access, so it is very easy to maintain and expand the network .

 

Network bridges are generally used in the following scenarios: wireless data collection, monitoring data transmission (outdoor and elevator), outdoor wireless coverage, outdoor long-distance wireless bridging, private ISP wireless broadband, unmanned monitoring station data return, etc.

 

  1. How to choose the right bridge

Wireless network bridge is a kind of wireless monitoring transmission equipment commonly used in the field of wireless monitoring. Although it is also a wireless device like wireless AP and wireless router, it is not used to build wifi coverage, but to wirelessly transmit video data. Like the switch in wired monitoring, wireless bridge is an important transmission device in wireless monitoring, and it is widely used in the two major fields of outdoor monitoring video transmission and elevator monitoring video transmission.

 

There are many types of wireless bridges on the market. How to choose a bridge that suits your needs? We will answer you from the following aspects.

 

① Transmission distance

The transmission distances required for wireless monitoring projects are not the same. There are also many transmission distances of wireless bridges. Some transmit 1 to 3 kilometers, some transmit 3 to 5 kilometers, some transmit 5 to 10 kilometers, and some transmit 20. More than kilometers, it must be determined according to the monitored transmission distance. As far as possible, the maximum transmission distance of the bridge is greater than the monitoring transmission distance. Because the rain, fog, snow and other weather in the actual application environment will cause the transmission performance of the bridge to decrease, the engineering construction should be predicted. Leave sufficient performance margin.

 

②Transmission bandwidth

There are many transmission rates of wireless bridges, such as 150Mbps, 3000Mbps, 450Mbps, 600Mbps, 900Mbps, etc. Which rate to choose can be determined according to wireless monitoring requirements. What users actually need to consider is the transmission performance of the bridge at a specific distance, not the theoretical bandwidth data. For example, the theoretical transmission bandwidth of the IP-COM AP625 bridge is 433Mbps. At a distance of 2 kilometers, the measured point-to-point transmission bandwidth can reach 200Mbps, and it can load 25 200W cameras without pressure.

 

③Working frequency

There are two mainstream working frequencies of wireless bridges, 2.4G and 5.8G, and the characteristics of the two bridges are different. Generally speaking, 2.4G wireless bridge is the current mainstream frequency band, with good compatibility and good diffraction ability, but its anti-interference ability is relatively poor, especially when used in urban areas, it is susceptible to wireless signal interference from other WiFi devices. The 5.8G channel is relatively pure, has better anti-interference ability, long transmission distance, but poor diffraction ability.

 

In urban areas, downtowns, long-distance transmission, large camera stream, 2.4G interference is more, choose a 5.8G wireless bridge. Others, such as short transmission distance, relatively remote, less co-frequency interference, etc., use 2.4G wireless bridge

 

④Antenna

The antenna is an important accessory of the wireless network bridge, which is used to transmit and receive wireless signals. Without the antenna, the wireless network bridge cannot realize communication. There are many types of antennas, including omnidirectional antennas and directional antennas. The omnidirectional antenna is used for short-distance coverage and transmission. For long-distance bridging, a directional antenna should be selected. The larger the antenna gain, the better the performance of the wireless network bridge.

 

⑤Power supply mode

The working environment of wireless bridges usually involves some complex outdoor environments, such as forests, ports, tunnels, reservoirs, etc., so power supply is a more troublesome issue. Choosing a wireless bridge that supports POE network cable power supply can solve this problem well. All IP-COM bridges support PoE injector power supply, and the power supply distance can reach 60 meters.

 

⑥Protection level

Wireless network bridges mostly work outdoors, and the environment is changeable, such as rain, rain, snow, high temperature, etc. The first requirements are waterproof, dustproof, heat-resistant, and anti-condensation. For a qualified wireless bridge, these “quality” are necessary.

 

⑦ Pairing method

There are currently three mainstream pairing methods for bridges: key pair pairing, dial code pairing, and automatic pairing. In terms of the simplicity of engineering applications, especially for projects where dozens or hundreds of bridges are installed at once, automatic matching is undoubtedly the best choice. The IP-COM bridge supports automatic pairing when the two bridges are powered on under the factory state, which greatly reduces the workload.

 

  1. Wireless network bridge installation requirements

Wireless network bridge is an important transmission equipment in wireless surveillance, and it is widely used in two major fields, outdoor surveillance video transmission and elevator surveillance video transmission. In addition to selecting a suitable wireless bridge, we also need bridge equipment that can give full play to its performance advantages after installation to assist users in the project. Therefore, we must pay more attention to some installation requirements and precautions of the wireless bridge to avoid various problems later.

 

①Installation height

During the wireless transmission of the wireless bridge, obstacles such as trees, buildings, and large steel structures will weaken and block wireless signals. In order to improve the wireless transmission performance and prevent the signal from being damaged and the signal is weak, users should try their best to ensure that there are no obstacles in the transmission route of the wireless bridge during installation to meet the mutually visible transmission conditions at both ends.

Visibility at both ends cannot be simply understood as point-to-point visibility, which means that there must be no obstacles or potential obstacles in the Fresnel zone (radio wave term) propagated by the antenna. The main radio frequency energy between the antennas is transmitted in this area, so the transmitting antenna must be high enough above the obstacle to maintain a line of sight path between it and the receiving antenna to ensure the normal operation of the communication link.

 

② Angle and signal debugging

Since the quality of the wireless bridge signal is directly related to the bandwidth and stability of the link, the wireless bridge signal must be further debugged after the installation is completed (you can adjust the signal strength by adjusting the direction of the antenna on both sides, the elevation angle, etc.) ). You can check the signal strength according to the signal status indicator of the bridge device (three lights, three signals are the best, two are normal, and one is poor) or software. Detailed installation steps of outdoor wireless AP

 

③Lightning rod requirements

When wireless network bridges are installed in the field, if there are no tall buildings or lightning rod protection nearby, lightning protection measures need to be considered. Usually, lightning rods are used. Generally, when installing in urban areas or surrounding lightning rod protection, separate lightning rods are not required.

From the characteristics of the lightning rod, it can be seen that the lightning rod is lightning-inducing, and the lightning rod will discharge in the grounding path when it is struck by lightning. Therefore, the lightning rod and the protected equipment need to be insulated and isolated, otherwise the lightning rod will have a lightning strike effect on other equipment when it is discharged. Because lightning rods are more likely to cause lightning discharge than ordinary equipment due to their tip discharge characteristics, if the lightning rod cannot be insulated from the protected equipment, it will increase the probability of lightning strikes for other equipment. Therefore, the grounding of the lightning rod needs to be separated from the grounding of the equipment and cannot share the same ground.

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④Power requirements

The normal power supply input voltage of the PoE power supply module of the bridge is 100V~240V and the output voltage is 24V-48V. Any voltage lower or higher than this will affect the normal operation of the device or cause abnormal damage to the PoE power supply module. In view of the unstable and high voltage supply in the field, it is necessary to design a set of PoE power supply solutions (such as stabilized power supply, UPS power supply) that adapt to the working voltage.

Since the network bridge is a precision electronic device, it has high requirements for power supply and is susceptible to the impact and influence of other power supply equipment, so the power supply of the network bridge should be separated from other high-power equipment such as pumping units and oil pumps. When taking power at the same location, UPS, stabilized power supply or isolation transformer should be installed to filter out the influence and interference of high-power motors on the power supply during operation.

When using a PoE module to power the bridge through a network cable, it is recommended that the distance does not exceed 60 meters. Beyond this distance, it is recommended to move the transmission line near the bridge to meet the recommended power supply distance requirements.

 

⑤ Equipment grounding requirements

The wireless network bridge should be grounded. If the device is not grounded, it will cause problems such as abnormal operation and damage of the device. The grounding resistance of the device should be less than 4 ohms, and it should not share the grounding with lightning rods and strong current lines. If a PoE power supply ground wire is used, grounding is also required. Users can use the super Category 5 (or above) shielded network cable with ground wire and PoE adapter for grounding, which can conveniently and effectively prevent static electricity and lightning damage. The grounding wire and the grounding point should be made of waterproof tape and water-proof cement according to the waterproof requirements to prevent the grounding point of the grounding wire from being oxidized and rusted due to long-term exposure to the air.

 

  1. How to set up wireless network bridge

There are 4 common wireless bridge transmission modes, the distribution is point-to-point, point-to-multipoint, relay, and reflection. Here, the first monitoring combined with the picture will briefly introduce the characteristics of these 4 wireless transmission modes.

 

①Point-to-point transmission

The point-to-point transmission mode is the simplest transmission mode, which is what we often call PTP. It is transmitted by a single device, and then received by a single device. One-to-one transmission and reception are simple and direct. The point-to-point transmission mode of the wireless bridge is often used in situations where the transmission distance is long, or the monitoring points are widely distributed, and point-to-multipoint transmission cannot be achieved.

 

②Point-to-multipoint transmission

The point-to-multipoint transmission mode is developed based on the point-to-point transmission mode. It is often expressed as one receiving end to multiple transmitting ends. It is often used in situations where the transmission distance is relatively short, there are many monitoring points, and the distribution is dense.

 

③Relay transmission

The relay transmission mode is because the transmitting end and the receiving end have unavoidable obstructions that block the microwave signal, so a relay device is added in the middle, so that the microwave signal can be smoothly transmitted to the receiving end through the relay device. This mode needs to increase Transfer equipment increases equipment cost input, so it is generally not used when it is not necessary.

 

④Reflection transmission

Reflective transmission is the use of objects other than the transmission equipment for microwave transmission and transmission. For example, the transmitting end and the receiving end cannot be visible, but there is a large building or a mountain with a smooth rock wall in the middle. By adjusting the angle of the device, wireless communication is carried out by reflecting microwave signals from buildings or mountain peaks.

Wireless bridges must be used in conjunction with antennas. There are two common wireless bridges and antennas, one is external, the other is internal. As the name suggests, the built-in antenna is installed inside the housing of the wireless bridge and is invisible on the surface. The built-in antenna is usually small and can be integrated with the bridge. The bridge and the antenna are integrated, which is convenient and compact and easy to carry. The disadvantage is that the transmission distance is relatively short. The transmission distance of the wireless bridge using the built-in antenna generally cannot exceed 10 kilometers. The external antennas come in several different shapes, which can be called different names according to different uses. For example, to distinguish by direction: there are directional antennas and omnidirectional antennas.

Directional antenna
The microwave signal is emitted at a fixed angle. Common angle antennas are 30 degrees, 60 degrees, 90 degrees, and 120 degrees. The angle of the directional antenna is limited, but because of this, the microwave signal transmitted through it can often be transmitted farther and more stable. The disadvantage is that the antenna must be aligned to achieve good microwave transmission. It is mostly used for point-to-point, point-to-multipoint, and relay link transmission.

Omnidirectional antenna
It transmits or receives microwave signals in all directions. Its microwave emission shape is a bit like an “apple”. There are fewer microwave signals directly above and below the omnidirectional antenna, which can be said to be black under the lamp. But its advantage is that it can perform wireless microwave transmission without aligning the angle. The disadvantage is that the transmission distance is short. It is mostly used for point-to-multipoint and relay link transmission.

In addition, the antennas are also divided into 2.4G and 5.8G frequencies. The wireless bridge of the corresponding frequency can only be used with antennas of the same frequency. For example, if a 2.4G wireless bridge is used, then 2.4G antennas must be used, and vice versa . Antennas can also be divided into single polarization and dual polarization antennas:

Single polarized antenna
It can only be used to transmit or receive microwave signals. Single-polarized antennas are mostly used at the transmitting or receiving end of point-to-point and point-to-multipoint wireless signals; while dual-polarized antennas are used to transmit and receive microwave signals at the same time, often used in wireless Relay relay of microwave signals.

Which antenna to use generally needs to be judged according to the site conditions, built-in, external, directional, omni-directional, single-polarized, dual-polarized, each has its own meaning, and users don’t need to worry too much when making a wireless plan. When determining which antenna to use, the user only needs to know the basic knowledge.