Engineering References → Calculators

RF Engineering Calculators

Standard RF engineering calculations for EMC and compliance work. All calculations assume free space unless otherwise noted.

RF Calculator

Wavelength, VSWR, power density, field levels, and unit conversions.

Wavelength from Frequency (Free Space)

Frequency (MHz)

λ (m)

—

VSWR from Forward / Reverse Power (W)

Forward Power (W)

Reverse Power (W)

VSWR

—

VSWR from Forward / Reverse Power (dBm)

Forward Power (dBm)

Reverse Power (dBm)

VSWR

—

Power Density & Field Level (Far Field)

Power into Antenna (W)

Antenna Gain (dBi)

Distance (m)

W/m²

—

dBµV/m

—

V/m

—

A/m

—

mW/cm²

—

Power to Generate Known Field (Far Field)

Required Field (V/m)

Antenna Gain (dBi)

Distance (m)

Required Power (W)

—

Gain from Antenna Factor (50 Ω system)

Antenna Factor (dB/m)

Frequency (MHz)

Gain (dBi)

—

dBm ↔ W (50 Ω)

dBm → W

—

W → dBm

—

dBm ↔ V (50 Ω)

dBm → V

—

V → dBm

—

dBm ↔ dBµV (50 Ω)

dBm → dBµV

—

dBµV → dBm

—

Radiated Power Calculator

Convert between ERP, EIRP, dBµV/m at 3m and 10m. Useful for comparing EMC test results to radiated power limits in compliance standards.

EIRP / ERP / Field Strength Converter

Input Field

Value

EIRP (mW)

—

EIRP (dBm)

—

ERP (mW)

—

ERP (dBm)

—

dBµV/m at 3m

—

dBµV/m at 10m

—

Field Strength Calculator

Convert between E, H, B, and power density units. Assumes a plane wave in free space (E = η₀H, S = E·H).

E / H / B / Power Density Converter

Input Field

Value

E (V/m)

—

dBµV/m

—

H (A/m)

—

dBµA/m

—

B (Tesla)

—

B (Gauss)

—

B (pT)

—

B (dBpT)

—

S (W/m²)

—

S (mW/cm²)

—

η₀ = 376.730 Ω  |  S = E²/η₀ = η₀·H²  |  1 mW/cm² = 10 W/m²

Free Space Path Loss

Signal attenuation between two isotropic antennas in free space.

Free Space Path Loss (dB)

Frequency

Frequency Unit

Distance

Distance Unit

Free Space Path Loss (dB)

—

FSPL = 20·log₁₀(d) + 20·log₁₀(f) − 147.55  |  d in metres, f in Hz

VSWR / Return Loss / Reflection Coefficient

Convert between VSWR, return loss (dB), reflection coefficient (Γ), and mismatch loss. Enter any one value to calculate the others.

VSWR ↔ Return Loss ↔ Reflection Coefficient

Input Type

Value

VSWR

—

Return Loss (dB)

—

Reflection Coeff. (Γ)

—

Mismatch Loss (dB)

—

Γ = (VSWR−1)/(VSWR+1)  |  RL = −20·log₁₀(Γ)  |  Mismatch Loss = −10·log₁₀(1−Γ²)

Skin Depth

Calculate the depth at which current density in a conductor falls to 1/e (~37%) of its surface value. Critical for shielding effectiveness and conductor loss calculations.

Skin Depth Calculator

Frequency

Frequency Unit

Material

Skin Depth (m)

—

Skin Depth (µm)

—

δ = √(ρ / (π·f·µr·µ₀))  |  µ₀ = 4π×10⁻⁷ H/m

Noise Figure / Noise Temperature

Convert between noise figure (dB), linear noise factor, and equivalent noise temperature. Reference temperature T₀ = 290 K.

Noise Figure ↔ Noise Temperature Converter

Input Type

Value

Noise Figure (dB)

—

Noise Factor (linear)

—

Noise Temperature (K)

—

Noise Temperature (°C)

—

NF(dB) = 10·log₁₀(F)  |  Te = (F−1)·T₀  |  T₀ = 290 K

Link Budget

Calculate received signal power accounting for transmit power, antenna gains, cable losses, and free space path loss. All power values in dBm, gains/losses in dB.

RF Link Budget Calculator

Tx Power (dBm)

Tx Antenna Gain (dBi)

Tx Cable Loss (dB)

Frequency

Frequency Unit

Distance

Distance Unit

Rx Cable Loss (dB)

Rx Antenna Gain (dBi)

FSPL (dB)

—

Received Power (dBm)

—

Rx = TxPow + TxGain − TxLoss − FSPL − RxLoss + RxGain

Coaxial Cable Attenuation

Estimate signal loss in common coaxial cable types. Attenuation scales with √f. Values are nominal — consult manufacturer datasheets for precision work.

Coax Cable Loss Estimator

Frequency

Frequency Unit

Cable Length

Length Unit

Cable Type

Estimated Attenuation (dB)

—

Nominal values scaled by √(f/f_ref). Consult manufacturer datasheet for precision applications.

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