How to Calculate Link Budget
What is Link Budget?
Calculates wireless link margin comparing transmit power and gains against path loss and noise. Determines link reliability and range.
Formula
Path loss = 20 log10(4πd×f/c)
Step-by-Step Guide
- 1Transmit power + antenna gain - cable loss - path loss + receive gain - noise figure = link margin
- 2Path loss = 20 log10(4πd×f/c)
- 3Positive margin = good signal; negative = insufficient range
- 4Typical 10-20 dB margin for reliability
Worked Examples
Input
Tx 30dBm, path loss 100dB
Result
-70dBm rx
Common Mistakes to Avoid
- ✕Not accounting for cable losses (2-3 dB typical)
- ✕Using theoretical max power instead of regulated output
Frequently Asked Questions
What's acceptable link margin?
Minimum 3 dB; 10+ dB good; 20+ dB excellent; accounts for fading and interference.
How do I improve link budget?
Increase transmit power, better antennas, lower frequency, shorter distance, or better receiver.
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