The receive sensitivity values are generally rated in dBm, and are usually in the range of dBm to dBm. The negative number indicates a very small signal -- tiny fractions of a milliwatt.
Below we have an example of two routers in relatively close range. They have a good connection because the signal strength between them is strong. Below, we can see the same routers, but with more distance between them.
In this case, the routers have a weaker connection because the signal is near the limit of what the routers can hear. The speed between the routers will be less. The optimal signal range for outdoor wireless equipment is between dBm and dBm. This will ensure the connection can maintain the highest bandwidth possible.
Wireless routers have different types of antennas. Some routers will have antennas built in, and sometimes the routers will have a choice of antenna you can attach to the router. There are many specific types of antennas, but three basic types are used most of the time, and will be useful in building a wireless network. The first type of antenna is also the most common--omnidirectional.
Using omnidirectional antennas has the benefit of creating connections in any direction. If there is enough signal between nodes, they should connect. The all-direction strength of these antennas comes with the drawback of transmitting a weaker signal.
Since the signal is going in all directions, it spreads out and gets weaker with distance very fast. If nodes or clients are far away, they may not connect well. Also, if there are only nodes or clients in one direction of the router, then the signals going in the opposite direction are wasted:. The next type of antenna is known as directional--it sends out a signal in a more focused way. There are two main types of directional antennas:. Sector Antenna Focused Antenna Sector antennas send out a pie-shaped wedge of signal - it can be anywhere between 30 degrees and degrees wide.
These are often long, rectangular antennas that are separate or integrated in to a router. A focused antenna sends out a narrow beam of signal - it is normally around 5 to 10 degrees wide, but it can be a little wider as well. These are often dishes or have a mesh bowl reflecting signal behind them.
Using directional antennas has the benefit of increasing the distance a signal will travel in one direction, while reducing it in all other directions. Since the signal is all going one way, the power that would be sent out in all directions with omnidirectional nodes is now focused, increasing the power in that direction.
It can also decrease the interference received at the node. There are fewer signals coming in to the antenna, since the node is only listening to signals from the direction it is pointing. This reduces the signals it needs to sort out, and allows it to focus on other signals more, increasing the quality of those connections.
However, directional antennas also have the drawback of requiring more planning to create links in your neighborhood. Since you are defining and limiting the areas where wireless signals go, you need to think about how those signals cover your neighborhood. If there are areas that are then left out, how will those areas be included in the network? Also, the node has a very powerful signal in a single direction. If omnidirectional units, or lower power units such as laptops, are connecting to the node, they may not connect properly.
The laptop will hear the node very well, but the directional node may not hear the laptop. This will create the situation where it looks like there is a strong signal, but you cannot connect. Networking concepts are important when dealing with wireless. If you are interested in learning more about Wi-Fi and wireless technology, there is a lot of information out there.
There are also excellent documents on Wikipedia about Wi-Fi and wireless signals. Similarly, an Internet search will most likely answer any questions you can think of, as wireless is a very popular technology. For more information on what frequencies are available in your country or regulatory area, please see this article on Wikipedia on wireless channels. Introduction This document covers the basics of how wireless technology works, and how it is used to create networks.
In addition to some background information, this document covers six basic concepts: Wireless signals - what they are and how signals can differ. Wireless devices - the differences and uses for receivers and transmitters.
Wi-Fi Modes - how networks are made up of clients, access points, or ad-hoc devices. Wi-Fi Signals - the unique characteristics of Wi-Fi, and how signals are organized.
Power and Receiver sensitivity - how far each wireless device can go, and how well a router can listen and filter out interference and noise. Antennas - how the type of antenna changes the way the router broadcasts. What is a wireless signal? Types of Wireless Signals There are many, many types of wireless technologies.
Frequency First of all, wireless signals occupy a spectrum, or wide range, of frequencies: the rate at which a signal vibrates. Example Frequency Ranges Below we can see the span of frequencies that are commonly used in communications. An un-modulated AM wave might look like: And a modulated AM radio wave has higher and lower energy amplitude waves indicating higher and lower audio frequencies in the signal: From left to right, we have the normal, un-modulated wave, then the lower amplitude wave representing low points in audio waves , then the higher amplitude wave representing crests or high points in audio waves.
A more detailed version of an AM signal is below: The audio signal is the wave on the top, with the corresponding Amplitude Modulated wave below it. An un-modulated FM wave might look like: And a modulated FM radio wave has higher and lower frequencies indicating higher and lower audio frequencies in the signal: From left to right, we have the normal, un-modulated wave, then the lower frequency wave representing lower audio amplitudes , then the higher frequency wave representing higher audio amplitudes.
Receivers and Transmitters When a device sends out a wireless signal, it is called a transmitter. Fill in some examples below each type: Transmitter Receiver Transceiver Examples: Examples: Examples: Do you use more transmitters, receivers, or transceivers throughout the day? Wi-Fi Signals When building a network, you will be using Wi-Fi technology, which has some unique characteristics you will need to know.
There are two types of Wi-Fi signal, based on the frequencies they use: 2. Many devices use it, so the signals can become more crowded and interfere with each other. Wireless networks are easy and inexpensive to set up, and most routers' web interfaces are virtually self-explanatory.
For more information on setting up and using a wireless network, check out the links that follow. Sign up for our Newsletter! Mobile Newsletter banner close. Mobile Newsletter chat close. Mobile Newsletter chat dots. Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe. How WiFi Works. Wireless networks make it easy to connect to the internet wherever you go.
Contents What Is WiFi? What Is WiFi? Here's what happens: A computer's wireless adapter translates data into a radio signal and transmits it using an antenna. A wireless router receives the signal and decodes it. The router sends the information to the internet using a physical, wired ethernet connection. They transmit at frequencies of 2. This frequency is considerably higher than the frequencies used for cell phones, walkie-talkies and televisions.
The higher frequency allows the signal to carry more data. The 2. In ideal conditions, the 5 GHz band has a max range of about feet 61 meters , but in the real world, it is much more prone to interference from walls, doors and other objects. For a while, its cost made it popular, but now it's less common as faster standards become less expensive. It can handle up to 11 megabits of data per second, and it uses complementary code keying CCK modulation to improve speeds.
It uses orthogonal frequency-division multiplexing OFDM , a more efficient coding technique that splits that radio signal into several sub-signals before they reach a receiver. This greatly reduces interference. It significantly improved speed and range over its predecessors. For instance, although It is less prone to interference and far faster than its predecessors, pushing a maximum of megabits per second on a single stream, although real-world speeds may be lower.
Like It is sometimes called 5G because of its frequency band, sometimes Gigabit WiFi because of its potential to exceed a gigabit per second on multiple streams and sometimes Very High Throughput VHT for the same reason. This standard extends the capabilities of First of all, the new routers allow an even higher data flow rate, up to 9. WiFi 6 also lets manufacturers install many more antennas on one router, accepting multiple connections at once without any worry of interference and slowdown.
Some new devices also connect on a higher 6 GHz band, which is about 20 percent faster than 5GHz in ideal conditions. WiFi Hot Spots " ". WiFi has enabled people to work anywhere they can get a signal, like at this coffee shop.
Building a Wireless Network " ". Smartphones, tablets, smart TVs and laptops all access the internet with the help of a router the device pictured with two antennas. The name of the network, known as its service set identifier SSID. The default setting is usually the manufacturer's name. The channel that the router uses.
Most routers use channel 6 by default. If you live in an apartment and your neighbors are also using channel 6, you may experience interference. Switching to a different channel should eliminate the problem. Your router's security options. Many routers use a standard, publicly available sign-on, so it's a good idea to set your own username and password. AES is considered the most secure. Public hot spots are either open or use any of the available security protocols, including WEP, so use caution when connecting away from home.
WiFi Protected Setup WPS , a feature that ties a hard-coded PIN to the router and makes setup easier, apparently creates a vulnerability that can be exploited by hackers, so you may want to turn off WPS if possible, or look into routers that do not have the feature. WPA3 was released in and became the security standard as of It aims to solve some of the vulnerabilities in WPA2 by putting much more complex encryption on both the router side and client side of the connection.
This encryption also changes over time, meaning if a hacker had managed to access an unauthorized connection at one point in time, they would be locked out again the next time they try to connect. In the case of Wi-Fi, the waves are produced on the electromagnetic spectrum. The electromagnetic spectrum consists of many different types of waves that make up the spectrum. The smallest type of waves is the gamma-ray, followed by X-rays. Further down the spectrum is the visible spectrum of light.
Further, still are micro-waves. Finally, the largest waves found at the other end of the spectrum are radio waves. Radio waves are the waves upon which data are transmitted. All types of waves can be measured by their amplitude and frequency. The amplitude of a wave measures how tall a wave is from its midpoint to its top or bottom.
The frequency of a wave measures how fast a wave is traveling. This also translates into how compressed the wave is or how many crests and troughs can be found per unit of distance.
Radio waves can be naturally generated through electric pulses. Both the amplitude and the frequency of a wave can be modulated. Amplitude Modulation which gives the name to AM radio is a process by which the amplitude i. Essentially, sound waves create vibrations in an electrical current flowing through a microphone or other device.
This current can then be transmitted out through an antenna in the form of a modulated radio waves. These sound modulated radio waves emanate spherically from the source and can then be picked up by a device designed to receive these radio waves and convert them back into sound waves.
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