How to Calculate Antenna Gain
What is Antenna Gain?
Calculates antenna directivity and gain compared to isotropic radiator. Shows how antenna concentrates power in preferred direction.
Formula
Gain (dBi) = 10 × log10(power density vs. isotropic)
Step-by-Step Guide
- 1Gain (dBi) = 10 × log10(power density vs. isotropic)
- 2Omnidirectional antennas 0-3 dBi
- 3Directional antennas 5-20+ dBi
- 4Gain trade-off: narrower pattern = higher gain
- 5Efficiency factor: practical gain < theoretical
Worked Examples
Input
Dipole antenna
Result
2.15 dBi
Common Mistakes to Avoid
- ✕Confusing antenna gain with amplifier gain
- ✕Not accounting for free space path loss
Frequently Asked Questions
What's the difference between dBi and dBd?
dBi: vs. isotropic point source; dBd: vs. dipole; dBi = dBd + 2.15.
How does antenna gain improve range?
6 dB gain = 2× power (doubles range); 10 dB = 10× power (3.16× range).
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