RF Link Budget CalculatorThis radio link budget calculator tool lets you quickly compute the Free Space Loss, Received Signal Strength, Fade Margin , Distance and more. You can use it for planning your RF links with our pulsAR Wireless Ethernet Bridges, or with other radios in any frequency band. It includes a Coaxial Cable Loss Calculator with pre-loaded loss parameters for a variety of LMR and Belden coaxial cables.
The calculator is a Java applet which should work in your browser. If you are not familiar with all the terms used you can read about the various parameters below the calculator. If you have any comments or suggestions for improving this calculator send us a message.
Microwave Link Budget Analysis - Parameters
OverviewThe calculator tool assumes a generic RF link between two sites. Site 1 is viewed as the transmitter and site 2 as the receiver. At each site you have a radio connected to an antenna through an RF cable. The calculator assumes you have "line of sight" between the two antennas. You can use our Fresnel zone and antenna height calculator to help determine if that is the case.
For any set of input values the calculator always computes the Free Space Loss and the Signal Strength at the Receiver. Additionally you choose a third output between the link Distance, Fade Margin , or Transmit Power . This lets you quickly answer the most common questions when designing a radio link:
1. How far can my radio link go while maintaining an acceptable Fade Margin ?
2. What Fade Margin will I get for a radio link of a certain distance?
You can change all the input parameters with the up/down "spinner" controls. As you change the input the calculator instantly updates the output values. By seeing the results immediately you can quickly evaluate trade-offs between different parameters.
Tx power in dBm = 10 * log (Tx power in mW)
Minimum signal strength at the input of the radio at which point the "Bit Error Rate (BER)" in the link is at a specified value. Most manufacturers use a BER of 1x10-6 (1 bit error in one million bits) to specify the radio receiver sensitivity. However make sure you check the specifications when comparing the sensitivity in radios from different manufacturers.
You can configure each of our pulsAR radio models to operate a four different RF speeds. Lower speeds give you a better sensitivity. The table below shows you the sensitivity values of each model when operating it at its maximum speed. Refer to the pulsAR data sheet for the sensitivity values at all the speeds supported:
Receiver Sensitivity . When you deploy a link you want to have a Receive Signal Strength that is sufficiently above the radio Receiver Sensitivity in order to survive signal fading due to a variety of factors. These factors might include slight misalignment of the antennas, losses due to fog and rain, etc. As a rule of thumb you should try to get at least 15 dB of fade margin in your links.
60% of the first Fresnel Zone " is clear of any obstructions. Refer to our Fresnel Zone Calculator page for more details.