# Wireless Calculators

Please select a wireless calculator: Power Budget | Free Space Loss | System Performance | Fresnel Zones | Power Conversion

Disclaimer: Due to the nature of radio frequency propagation and the numerous factors that can affect operating range we do not guarantee that you will achieve any specific range for your application. These wireless calculators are for estimation purposes only. L-com does not guarantee their accuracy or applicability. L-com cannot be held liable for wireless installations based on these tools. Customers should use these tools at their own risk.

## Power Budget Wireless Calculator- Total power of your system in dBm

• MINUS cables and connectors losses
• PLUS antenna gain

Enter one parameter in each column (or leave blank) depending on what is know and the calculator will supply the appropriate conversions automatically. Up to 2 decimal places may be entered as 0.xx or .xx.

Note: Connector loss is generally minimal unless you have many of them or if your cable is very short.

See the calculations and equations used for this wireless calculator.

 Radio and Antenna Transmit Power Antenna Gain Power mW OR dBm dB(i) dB Cable Loss Cable Properties (per 100 ft or m) Cable Length dB (100 ft) OR dB (100 m) feet OR meters dB Connector Loss Frequency in MHz No. of Connectors MHz. No. dB Budget dB

## Free Space Loss Wireless Calculator - Power loss over distance

Free Space Loss is the loss of power over distance (assuming no FRESNEL Effect and nothing in the way). This is a very idealised calculation and in practice everything interferes with the signal but this will give you a reasonable approximation of the actual loss over distance.

Enter the system Frequency in MHz and the distance in either Kilometers (Km) or Miles below and then click the 'Calculate' button. 1 GHz = 1000 MHz e.g. 2400 = 2.4 GHz.

See the calculations and equations used for this wireless calculator.

 Frequency Distance Result MHz Km OR Miles dB

## Fresnel Zones Wireless Calculator - How much more than LOS or how high should my antenna be?

This calculator defines how much clearance you need (you will require more than simple Line-of-Sight) and for longer links > 3 Km (2 miles) whether you may have a ground clearance problem.

Enter the Total link distance (in Miles or Kilometers), if you do not enter an Obstacle distance (in Miles or Kilometers) the calculator will use the mid-point for all calculations (Note: assumes antennas at same height). Finally enter the system Frequency in MHz and then click the 'Calculate' button. 1 GHz = 1000 MHz e.g. 2400 = 2.4 GHz.

The calculator will generate the radius of the 1st Fresnel zone only (at the obstable point or the mid-point), the 60% (no obstacle) radius and the height of the effective earth curvature at the mid-point of the Total link distance using the effective earth radius.

See the calculations and equations used for this wireless calculator.

 Total Link Obstacle Distance 1st Fresnel Zone Radius Km OR Miles Km OR Miles m at Km ft at Miles Frequency 60% No Obstacle Radius MHz m ft Earth Height (mid-point) m ft

## System Performance Wireless Calculator - How far will it go, will it get there or what is my Operating Margin?

This wireless calculator will give you one of three answers:

1. If you leave distance blank it will apply the defined SAD factor (or default to 30%) to the Operating Margin and supply the max. distance (in Km and Miles) at which the Margin operates.
2. If you enter the distance it will calculate the Operating Margin and the SAD factor.
3. If you enter distance but leave RX or TX antenna gain (or both) blank it will apply the chosen SAD factor (or default it to 30% if none supplied) and generate the required antenna power. If both are left blank it will calculate a symmetrical antenna gain.

## To RESET any parameter just set it to BLANK before clicking 'Calculate'

Notes: RX Sensitivity is always expressed as a negative dBm (- dBm) and is the lowest power of signal your radio can handle. RX Sensativity should be listed in your radio manual and will be typically in the range of -70 to -110 dBm.

Note: If you solve for TX antenna (you leave it blank) and define a specific SAD factor it is applied to the TX budget and any TX antenna value will include this factor. If you then click Calculate again without changing anything, the SAD factor will be calculated to include the supplied TX antenna value and thus may show a lower value than the original one.

See the calculations and equations used for this wireless calculator.

 Frequency Distance FS Loss MHz Km OR Miles dB TX Power TX Cable TX Antenna Total TX dBm OR mW dBm dB dB RX Sensitivity RX Cable RX Antenna Total RX dBm dB dB dB Margin RX Power SAD Factor Theoretical dBm % dB

## Power Conversion Wireless Calculator - milliWatts to dBm (and vice versa)

Power in milliWatts to dBm (and vice versa) . Enter the 'Transmit Power' in milliWatts OR the 'Power Ratio' in dBm and click the appropriate 'Calculate' button. 1 Watt = 1000 milliWatts.

See the calculations and equations used for this wireless calculator.

 Transmit Power Result mW dBm Power Ratio Result dBm mW

## Power Budget Calculations

1. mW to dBm = 10Log10(mW)
2. feet to meters = .3048
3. meters to feet = 3.28
4. Calculator normalises all distances to kilometers and meters
5. Connectors loss = 0.10 * square root (frequency in GHz)

## Free Space Calculations Free space loss = 36.56 + 20Log10(Frequency) + 20Log10(Distance in miles)

1. Calculator normalises all distances to miles
2. Miles to Kilometers = 1.609
3. Kilometers to miles = 0.621

## Fresnel Zone Calculations

1. Calculator normalises all distances to kilometers and meters
2. Miles to Kilometers = 1.609
3. Kilometers to miles = 0.621
4. feet to meters = .3048
5. meters to feet = 3.28
6. 1st Fresnel Zone radius (Km) = 17.3 x Sqr root ((Obstacle Distance x (Total Link - Obstacle Distance)) / (Frequency in GHz x Total Link))
7. 1st Fresnel Zone radius (miles) = 72.6 x Sqr root ((Obstacle Distance x (Total Link - Obstacle Distance)) / (Frequency in GHz x Total Link))
9. Radius of nth Fresnel zone (meter) = sqr root ( (n x wave length x Obstacle distance x (Total Link - Obstacle Distance)) / Total Link )
10. wave length (meters) = speed of light (299,792,458 m/s) / frequency in Hz
11. Earth curvature calculation = (Total Link) 2 /(8 * effective earth radius)
13. Earth radius = 3963 miles, 6378 Km

## System Performance Calculations

1. Calculator normalises all distances to miles and feet during calculations.
2. Free space loss = 36.56 + 20Log10(Frequency) + 20Log10(Dist in miles)
3. mW to dBm = 10Log10(mW)
4. dBm to mW = 10(dBm/10)
5. RX Power = Margin - RX sensitivity
6. Theoretical margin = TX power budget + RX power budget - free space loss
7. SAD factor = Theoretical margin/TX power budget * 100 and shows the percentage of spare power on transmission.

## dBm to milliWatts Calculations

1. mW to dBm = 10Log10(mW)
2. dBm to mW = 10(dBm/10)