Link Budget for Communication Systems

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Propagation loss, multipath and noise are factors that can prevent ideal communication between a source and destination. To mitigate these challenges, communication systems employ various techniques and hardware components, including directional antennas, transmitter power, low noise amplifiers and filters. A crucial tool for assessing system performance in relation to these parameters is the link budget, which shows the relationship between system characteristics and the pre-detection signal-to-noise ratio (S/N). By employing a link budget, system designers can make informed decisions and determine tradeoffs to achieve a desired S/N ratio.


You can use this Demonstration to explore the tradeoffs involved in communication link design. You can vary the key system parameters carrier frequency (in MHz), transmitter power (in ), path-loss exponent, receiver antenna temperature (in kelvin), receiver noise figure (in dB), bandwidth (in MHz) and transmitter/receiver antenna sizes (in meters). It is worth noting that the relationship among antenna size, configuration and antenna gain can be complex. However, for the purposes of this Demonstration, a parabolic reflector antenna serves as a proxy for the relationship between the relative size of the antenna and its gain. Consequently, the calculated S/N is not valid if the calculated antenna gain (as displayed) is less than 0 dB, as a gain of 0 dB corresponds to an isotropic antenna. This Demonstration calculates the antenna gains. The S/N is presented as a function of the distance between the transmitter and receiver, which influences S/N values over a selected range of distances.


Contributed by: Victor S. Frost (August 25)
Open content licensed under CC BY-NC-SA


The following parameter definitions and relationships are used:

is the carrier frequency (Hz)

is the transmitter power (W)

is the wavelength with m/s

is the path loss equal to with distance and path loss exponent (dB)

is the antenna gain with parabolic antenna diameter ( is the transmitter and is the receiver)


is the antenna temperature (K)

is Boltzmann's constant

is the bandwidth (Hz)

is the receiver noise figure



[1] S. Haykin and M. Moher, Introduction to Analog and Digital Communications, 2nd ed., Hoboken, NJ: Wiley, 2007.

[2] L. W. Couch, Digital and Analog Communications Systems, 7th ed., Upper Saddle River, NJ: Pearson/Prentice Hall, 2007.

[3] V. S. Frost. "Introduction to Communication Systems: An Interactive Approach Using the Wolfram Language." University of Kansas Libraries. (Jul 5, 2023)


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