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Calcimator

Repeater Coverage Calculator

Estimate repeater coverage radius from antenna height, power, terrain type, and mobile antenna parameters.

Inputs

m
W
MHz
dBi
m

Results

Effective Coverage Radius

46.25 km

≈ 140 Eiffel Towers

Coverage Area

6,718.9 km²

Signal Margin at Edge

57 dB

Radio Horizon (Clear)46.25 km
Coverage Area2,594.2 mi²
Signal at Edge-59 dBm
Repeater Horizon41.2 km
Mobile Horizon5.05 km
Handheld Erp Dbm36.99
How to Use This Calculator
  1. Enter the repeater antenna height above average terrain (HAAT) in feet.
  2. Set repeater effective radiated power (ERP), operating frequency, and mobile antenna gain (dBd).
  3. Enter the mobile antenna height and select terrain type (flat, hilly, or mountainous).
  4. Review effective coverage radius (km/mi), radio horizon, coverage area, and signal at edge of coverage.

How the result changes with Repeater Antenna Height (HAAT)

Repeater Antenna Height (HAAT)Effective Coverage RadiusCoverage AreaSignal Margin at Edge
20564.04 km12,882.2 km²54.1 dB
703114.28 km41,032 km²49.1 dB
1,302153.71 km74,224.6 km²46.5 dB
1,801179.89 km101,664.7 km²45.2 dB

What each input means

Repeater Antenna Height (HAAT)
Height above average terrain in meters (key factor in coverage)
Repeater ERP
Effective radiated power in watts (Tx power × antenna gain - losses)
Frequency
Repeater output frequency (144-148 MHz for 2m, 420-450 MHz for 70cm)
Mobile Antenna Gain
Mobile/portable antenna gain (rubber duck: 0 dBi, mag mount: 3-5 dBi)
Mobile Antenna Height
Mobile antenna height above ground (vehicle roof: 1.5m, handheld: 1m)
Terrain Type
1=Flat/Open, 2=Suburban, 3=Urban, 4=Dense Urban/Mountain

How this is calculated

Formula

d = 4.12 × √h₁ + 4.12 × √h₂ (adjusted for terrain)

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Repeater Antenna Height (HAAT) = 100, Repeater ERP = 50, Frequency = 146, Mobile Antenna Gain = 3 = 6 input(s) provided
  2. Calculate Effective Coverage Radius
    Effective Coverage Radius
    46.25 = 46.25
  3. Calculate Coverage Area
    Coverage Area
    6718.9 = 6718.9
  4. Calculate Signal Margin at Edge
    Signal Margin at Edge
    57 = 57
  5. Calculate Radio Horizon
    Radio Horizon
    46.25 = 46.25
  6. Calculate Coverage Area
    Coverage Area
    2594.2 = 2594.2

Engine last updated . Checked against 2 independently-derived tests — how we verify calculators.

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