In link budget planning, how does increasing EIRP affect the practical range?

• A. It increases by 3 dB for every doubling of range.
• B. Each 6 dB increase in EIRP doubles the range.
• C. EIRP does not affect range.
• D. A 10 dB increase changes range unpredictably.

Answer: (B)

In a wireless link, the received power in free space scales with EIRP divided by the square of the range: Pr ∝ EIRP / R^2. To keep the received power above the minimum needed for reliable reception, the range must grow with the square root of EIRP. That means increasing EIRP by a factor of 4 (which is +6 dB) allows the range to double, since R ∝ sqrt(EIRP). So a 6 dB boost in EIRP provides a twofold increase in practical range. By the same logic, a 3 dB increase (EIRP × 2) would only increase range by about 1.41×, and a 10 dB increase (EIRP × 10) would raise range by about 3.16×. The statement that each 6 dB increase doubles the range is the best description of this relationship.