Link Budget Calculator

COST 231 Walfisch-Ikegami

Semi-empirical model for urban environments in the 800–2000 MHz range. Combines the Walfisch-Bertoni and Ikegami models with empirical adjustments from the COST 231 project. Computes path loss with and without line-of-sight (LoS / NLoS).

System Parameters

Tx–Rx Distance

Frequency

MHz

Base Station Height

Mobile Station Height

Street–Link Angle

Street Width

Building Separation

Environment

Buildings in Path

Building 1 m

Link Budget (Power Parameters)

Transmitter Power

dBm

Transmitter Antenna Gain

dBi

Receiver Antenna Gain

dBi

Miscellaneous Losses

Results

Satellite RF — ITU Model

Link budget calculation for RF satellite systems per ITU standard. Considers a transparent transponder with an HRDP link (uplink + downlink). Operates in C, X, Ku, Ka bands (up to ~20 GHz).

Uplink Parameters (Ground Station → Satellite)

Ground Station Transmitter Power

dBW

Uplink Frequency

MHz

Ground Station Antenna Gain

dBi

Ground Station Pointing Loss

Satellite Receive Antenna Gain

dBi

Satellite Pointing Loss (UL)

Downlink Parameters (Satellite → Ground Station)

Satellite Transmitter Power

dBW

Downlink Frequency

MHz

Satellite Transmit Antenna Gain

dBi

Satellite Pointing Loss (DL)

Ground Station Receive Antenna Gain

dBi

Ground Station Pointing Loss (DL)

Orbital & Link Constants

Orbital Altitude

Elevation Angle

Atmospheric Losses

Satellite Noise Temperature

Results

Optical Satellite — FSO Downlink (Lasercom)

Link budget calculation for Free Space Optical (FSO) communications. Based on the Giggenbach et al. model for LEO–ground station downlink. Optical range: ~1000–1550 nm.

Transmitter Parameters (Satellite)

Optical Wavelength λ

Average Transmitter Power

dBm

Transmitter Internal Losses

Beam Divergence Angle θ_div

rad

Radial Jitter Sigma σ_BW

rad

Link Geometry

Orbital Altitude H₀

Ground Station Altitude H_GS

Elevation Angle ε

Atmospheric & Receiver Parameters

Zenith Transmission T_z

—

Scintillation Loss a_sci

Receiver Aperture Area A_Rx

m²

Receiver Internal Losses a_Rx

Results

Display Theme

Unit Dictionary

Symbol	Parameter	Unit
P_Tx	Transmitted Power	dBm / dBW
P_Rx	Received Power	dBm / dBW
G_Tx	Transmit Antenna Gain	dBi
G_Rx	Receive Antenna Gain	dBi
L_FS	Free Space Path Loss	dB
L_rts	Rooftop Diffraction Loss	dB
L_msd	Multi-Screen Diffraction Loss	dB
EIRP	Effective Isotropic Radiated Power	dBW
C/N	Carrier-to-Noise Ratio	dB
G/T	Satellite Figure of Merit	dB/K
FSL	Free Space Loss	dB
λ	Wavelength	m / nm
f	Frequency	Hz / MHz / GHz
d	Link Distance	km
k	Boltzmann Constant	−228.6 dBJ/K
h_t	Transmitter Antenna Height	m
h_r	Receiver Antenna Height	m
ω	Street Width	m
B	Building Separation	m
θ_div	Beam Divergence Angle	rad
σ_BW	Radial Jitter Sigma	rad
A_Rx	Collection Aperture Area	m²

Unit Converter

Conversion Type

Key Equations

General Link Budget

P_Rx = P_Tx + G_Tx − L_Tx − L_FS − L_M + G_Rx − L_Rx

Free Space Loss (FSL)

FSL = 32.5 + 20·log(d_km) + 20·log(f_MHz)

COST231 — LoS Loss

P_LoS = 42.64 + 26·log(d) + 20·log(f)

COST231 — NLoS Loss

P_NLoS = L₀ + L_rts + L_msd

EIRP

EIRP = 10·log(P_T) + G_T [dBW]

G/T (Satellite)

G/T = G_R − 10·log(T_sat)

Optical — Free Space Loss

a_FSL = 10·log(λ² / (16π²·L²))