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Wireless Calculator

Introduction

Wireless LAN Calculator

Various questions can arise when setting up a wireless connection. For example, what is the transmission power available over a given distance, what is the maximum possible separation of a transmitter and receiver while maintaining a certain link quality, or how do you choose a suitable model from our various antennas? The TP-LINK wireless calculator will provide you with answers to these questions. Actual wireless connection will vary because of the network conditions and environment factors, and the results calculated by the program is for your reference only.

Before we start using the Wireless Calculator, it is useful to know how it works.

The TP-LINK wireless calculator contains three different functions:

  1. Distance Calculation
  2. Link Budget Calculation
  3. Antenna Selection

Which function should you choose?

If you want to see the possible maximum separation of the transmitter and receiver while maintaining a certain link quality at different data transfer rates, you can choose the distance calculation function.

If you want to see the reliability of your wireless connection while the transmitter and receiver are working at a certain distance, you can choose the link budget calculation function.

If you want to find suitable transmitter and receiver antennas from our various antennas of which can meet the need of getting a good performance at a given distance, you can choose the function of antenna selection.

Distance Calculation

The majority of the power of a radio signal will be lost in the air. Even in a perfect vacuum, a radio wave loses some of its energy since some energy is always radiated in directions other than the link axis. The Free Space Path Loss (FSPL) measures the power loss in free space without any obstacles. So for end-users, it is important to know the approximate distance between the transmitter and receiver while maintaining a certain link quality at different data transfer rates.

Related formula

FSPL depends on two parameters: First is the frequency of radio signals;Second is the wireless transmission distance. The following formula can reflect the relationship between them.

FSPL (dB) = 20log10(d) + 20log10(f) + K

d = distance
f = frequency
K= constant that depends on the units used for d and f
If d is measured in kilometers, f in MHz, the formula is:

FSPL (dB) = 20log10(d)+ 20log10(f) + 32.44

From the Fade Margin equation, Free Space Path Loss can be computed with the following equation.

Free Space Path Loss=Tx Power-Tx Cable Loss+Tx Antenna Gain+Rx Antenna Gain - Rx Cable Loss - Rx Sensitivity - Fade Margin

With the above two Free Space Path Loss equations, we can find out the Distance in km.

Distance (km) = 10(Free Space Path Loss – 32.44 – 20log10(f))/20

The Fresnel Zone is the area around the visual line-of-sight that radio waves spread out into after they leave the antenna. You want a clear line of sight to maintain strength, especially for 2.4GHz wireless systems. This is because 2.4GHz waves are absorbed by water, like the water found in trees. The rule of thumb is that 60% of Fresnel Zone must be clear of obstacles. Typically, 20% Fresnel Zone blockage introduces little signal loss to the link. Beyond 40% blockage the signal loss will become significant.

FSPLr=17.32*√(d/4f)

d = distance [km]
f = frequency [GHz]
r = radius [m]

Link Budget Calculation

A wireless link budget for a point-to-point radio link accounts for all the gains and losses from the radio transmitter (source of the radio signal), through cables, antennas and free space to the receiver. Estimating the value of the "power" in the different parts of the radio link is necessary to be able to make the best design and the most adequate choice of equipment.

Link budget is often referred to as Fade Margin or System Operating Margin in the calculation. The exact amount of the fade margin required for a wifi system depends on the desired reliability of the link, but a good rule of thumb is 20-30 dB.

For uses, especially those who want to know the reliability of their wireless connection when the transmitter and receiver are working at a certain distance from each other, this function is ideal.

Note:

  • Excellent: Link should work with high reliability, ideal for applications demanding high link quality. Fade Margin level is more than 22dB.
  • Good: Link should give you a good surfing experience. Fade Margin level is 14~22dB.
  • Normal: Link would not be stable all the time, but should work properly. Fade Margin level is 14dB or lower.

Related formula

Fade Margin = Received Signal - Receiver Sensitivity

Where

Received Signal = Tx Power - Tx Cable Loss + Tx Antenna Gain - Free Space Path Loss + Rx Antenna Gain - Rx Cable Loss

Antenna Selection

For outdoor applications, an antenna is a very important device. A suitable antenna can help you maintain reliable link quality while at the same time save your money. For end-users, it is important to find a suitable antenna. In this function, you can find a suitable transmitter or receiver antenna from the variety of the antennas that TP-LINK offers to find the right antenna for you that will maintain a certain link quality at the required distance.

Related formula

To find a suitable antenna, it can be done by calculating the antenna gain from the two Free Space Path Loss equations.

To find out Transmitter Antenna Gain (assuming you have Receiver Antenna Gain information)

Tx Antenna Gain = Fade Margin - Tx Power + Tx Cable Loss + Rx Cable Loss + Rx Sensitivity + 32.44 + 20 log10(f) + 20 log10(d) - Rx Antenna Gain

d = distance [km]
f = frequency [MHz]

To use this function, you need to know the distance & fade margin and select transmitter & receiver access point, optional cables & receiver antenna.

To find out Receiver Antenna Gain (assuming you have Transmitter Antenna Gain information)

Rx Antenna Gain = Fade Margin - Tx Power + Tx Cable Loss + Rx Cable Loss + Rx Sensitivity + 32.44 + 20 log10(f) + 20 log10(d) - Tx Antenna Gain

d = distance [km]
f = frequency [MHz]

To use this calculator, you need to know the distance & fade margin and select transmitter & receiver access point, optional cables & transmitter antenna.

With the computed antenna gain value, you will be able to find a suitable antenna.

Distance Calculate

Help

This function is used for computing the ideal distance for your TP-LINK wireless devices.

  1. Step 1: Select your transmitter and receiver access point/wireless router from the drop-down list
  2. Step 2: If you have cables connected, select your model from the drop-down list
  3. Step 3: Select your required link quality level (excellent/good/normal)
  4. Step 4: Select your transmitter and receiver antennas from the drop-down list and click the Calculate button

Antenna selection

Help

This function can help you find the suitable antennas from the various TP-LINK antennas.

  1. Situation one: I do not have an antenna.
    In this situation, the results assume that the transmitter and receiver antennas have the same gain.
    1. Step 1: Select your transmitter and receiver access point/wireless router from the drop-down list
    2. Step 2: If you have cables connected, select your model from the drop-down list
    3. Step 3: Select your required link quality level (excellent/good/normal) 
    4. Step 4: Click Find button to get the results
  2. Situation two: I already have a transmitter or receiver antenna.
    1. Step 1: Select your transmitter and receiver access point/wireless router from the drop-down list
    2. Step 2: If you have cables connected, select your model from the drop-down list
    3. Step 3: Select your required link quality level (excellent/good/normal) 
    4. Step 4: Select your transmitter antenna (receiver antenna) from the drop-down list and click the Find button to find a suitable receiver antenna (transmitter antenna)
  • Transmitter

  • Receiver

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