Free-Space Path Loss
Signal power lost simply by spreading through free space, growing with both distance and frequency.
Formula
Variables
Example
At 100 km, 1090 MHz: FSPL ≈ 20×2 + 20×3.04 + 32.44 ≈ 133 dB
Did You Know?
Path loss quadruples (−6 dB) each time distance doubles, which is why long-range ADS-B and radar links need high transmit power and sensitive receivers.
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