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Link Budget Calculator

Calculators / RF Link Budget

RF Link Budget
Calculator

Complete end-to-end RF link budget: EIRP → free-space path loss → received power → SNR → link margin. Essential for wireless communication system design, satellite link analysis, and RF system planning. Full waterfall budget breakdown.

TRANSMITTER Pt=— Gt=— dBi L_t=— dB EIRP=— PATH LOSS FSPL=— L_atm=— Total=— d=— RECEIVER Pr=— Gr=— dBi L_r=— dB sens=— MARGIN +— dB ✔ LINK OK SNR=— dB TX Propagation RX Result
Distance 10.0 km
1 m500 km
TX (EIRP) Path Loss RX / Margin

⚙ Link Budget Engine

📡 Transmitter

20 dBm = 100 mW

dBi

0 dBi = isotropic. Half-wave dipole = 2.15 dBi

dB

EIRP = Pt + Gt − cable = —

dB

Antenna beam misalignment loss

📶 Propagation

λ = — cm

Free-space link distance

Total atm loss = rate × distance

📻 Receiver
dBi

0 dBi = isotropic. High-gain dish: 30–50 dBi.

dB

Coax run from antenna to receiver

dBm

Minimum detectable signal level

dB

LNA: 2–4 dB, typical receiver: 6–10 dB

Advanced / SNR Parameters

MHz

Used for thermal noise floor calculation

Minimum Eb/N0 for target BER

dB

Hardware non-idealities, modem imperfections

dB

Design target fade margin (typical: 10–20 dB)

Link Budget Summary

Link Margin dB
−20 dB0+10+20+40 dB
Received Power (Pr)
EIRP
FSPL
SNR at RX

Total path loss
Thermal noise floor
Max range (at margin=0)
Link status
Enter parameters above to calculate.

Complete Link Budget Waterfall

#ParameterValue (dB)Running Total (dBm)Note
Enter values above to generate budget

📖 Theory

A link budget is an accounting of all gains and losses in an RF communication system from the transmitter output to the receiver decision circuit.

Budget Equation

Pr = Pt + Gt − L_t − FSPL − L_atm − L_pol + Gr − L_r

All in dB/dBm. Every gain adds, every loss subtracts.

Link Margin

M = Pr − S
M = Pr − (N₀ + NF + BW + Req_SNR)

M > 0 → link works. Design for M ≥ 10–20 dB.

FSPL Formula

FSPL(dB) = 20·log(d_km) + 20·log(f_GHz) + 92.44

📊 Received Power & Margin Viewer

Live Charts | ◉ Pr vs distance — sensitivity threshold shown
View
Max Distance 100 km
TX Power 20 dBm
Received Power (dBm) vs Distance Distance → Pr (dBm) Sensitivity
Link Budget Insights

Enter link parameters to see system design insights.


Common Applications

📡

Wireless Communication

Design WiFi, cellular, LoRa, ZigBee, and Bluetooth links. Determine maximum range and required antenna gain for a given link margin.

🛰️

Satellite Links

LEO, MEO, and GEO satellite uplink/downlink budgets. Calculate EIRP, G/T, and C/N₀ for earth station and spacecraft design.

📊

RF System Planning

Network coverage planning, base station siting, repeater spacing, and spectrum efficiency analysis for licensed and unlicensed bands.

🔬

Research & Education

Teach and study wireless propagation, link margin concepts, modulation-SNR requirements, and noise figure effects on system performance.

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