mW → dBm
Result
20.00 dBm
dBm = 10 × log₁₀(mW)
dBm → mW
Result
100.000 mW
mW = 10 ^ (dBm ÷ 10)
Power ratio → dB · for Rules of 3 / 5 / 10 exercises (WS1)
dB equivalent
3.01 dB
≈ Rule of 3 (2× = +3 dB)
dB = 10 × log₁₀(ratio)
Quick reference
Common values · click any chip to load into converters above
Display units:
Frequency → Wavelength
Wavelength
12.430 cm
0.12430 m
λ = c ÷ f | c = 299,792,458 m/s
Wavelength → Frequency
Frequency
2.4120 GHz
2412.0 MHz
f = c ÷ λ
Wi-Fi channel center frequencies · 2.4 / 5 / 6 GHz · click to load
dBd → dBi
Result
7.99 dBi
dBi = dBd + 2.14
dBi → dBd
Result
5.85 dBd
dBd = dBi − 2.14
Common antenna gains · click to load
Vendor proprietary power ladder · WS4 · enter Level 1 max power to generate full table
Many vendors use a 1–N scale where each step down halves the power (−3 dB). Enter the maximum output power at Level 1 and the number of levels your AP uses.
Level 1 (mW)
100.0 mW
Each level = ½ power = −3 dB from level above. Applies to Cisco, Aruba, and most enterprise AP vendors.
Transmit chain → EIRP & IR · WS6
IR = TX power − cable/connector loss | EIRP = IR + antenna gain (dBi)
Back-solve → find required TX power · WS6 exercises 16 & 17
Given a target EIRP you must hit and your cable + antenna, what transmitter output power (Pt) do you set?
Required Pt = target EIRP − antenna gain + cable loss
Distance units:
Path Loss Quick Lookup
FSPL — forward · freq + distance → path loss
Free Space Path Loss
—
FSPL = 20·log₁₀(d_km) + 20·log₁₀(f_MHz) + 32.45
Max range — reverse · freq + path loss budget → distance
Maximum range
—
d = 10^((FSPL − 20·log₁₀(f_MHz) − 32.45) ÷ 20)
Full Link Budget
Transmit side
Receive side
Path
Results
FSPL = 20·log₁₀(d_km) + 20·log₁₀(f_MHz) + 32.45 | RSS = EIRP − FSPL + RX gain − losses
RSS vs. distance — live visualization · adjust any parameter to see the curve update
The blue curve shows received signal strength vs. distance using current settings. The red dashed line is your RX sensitivity threshold. The shaded zone below the red line is where the link fails. The vertical marker shows your current distance.
Distance units:
The first Fresnel zone is an ellipsoidal region surrounding the direct path between two antennas. Obstructions inside it cause diffraction loss even when the geometric line of sight is clear. The standard minimum clearance is 60% of the first Fresnel zone radius. Earth bulge becomes significant on paths longer than ~5 km and must be added to the required clearance height.
Path parameters
Results at obstacle position
r₁ = √(λ·d₁·d₂/d) · r₁_max = ½√(λ·d) · min clearance = 0.6·r₁
earth bulge = d₁·d₂ / (2·k·Rₑ) k=4/3, Rₑ=6370 km
earth bulge = d₁·d₂ / (2·k·Rₑ) k=4/3, Rₑ=6370 km
Common P2P scenarios
First Fresnel zone profile · full path · adjust parameters above to update
Cyan line: first Fresnel zone radius at each point along the path. Orange dashed line: 60% minimum clearance requirement — all obstructions must clear this height above the direct path. Red dashed line: earth bulge (shown when path ≥ 2 km).
Antenna downtilt steers the beam's main lobe toward the intended coverage area, reducing interference to co-channel cells beyond the target zone. Enter either downtilt → coverage distance, or target coverage distance → required downtilt. All distances assume flat terrain; add trig correction for sloped terrain.
Downtilt → Coverage distance
Coverage distance → Required downtilt
Vertical HPBW reference — by antenna type
Beam coverage profile · side view · bore-sight and HPBW boundaries
Side-view projection to ground plane. Cyan line: bore-sight. Orange dashed lines: half-power beam boundaries. Adjust height, tilt, and HPBW to see the coverage footprint change in real time.
θ = atan(h/d) · d_bore = h/tan(θ) · d_near = h/tan(θ+HPBW/2) · d_far = h/tan(θ−HPBW/2)