ERP Calculator
Calculate Effective Radiated Power (ERP) from transmitter power, antenna gain, and feed-line loss. Also computes equivalent EIRP and related engineering values.
3
Inputs
Live
Math
3
Related
Enter parameters and click Calculate to view results
Formula & Theory
ERP = PT × 10^((GdBd − L)/10), EIRP = ERP + 2.15 dBThis formula is used to calculate antenna parameters for erp calculator.
Overview
The ERP Calculator helps RF engineers, wireless network designers, broadcast engineers, amateur radio operators, and students calculate Effective Radiated Power (ERP) from transmitter power, antenna gain, and feed-line loss. It also computes equivalent EIRP, transmitter power in dBW and dBm, antenna input power, feed-line efficiency, net system gain, and linear gain. This calculator is ideal for RF link budget analysis, antenna system design, wireless communication, broadcasting, microwave links, satellite communication, cellular networks, and regulatory compliance.
Input Guide
Enter Transmitter Power, Antenna Gain, Feed-Line Loss exactly in the units shown by this erp. Check the operating band, unit prefix, and decimal position before calculating; these are the inputs used by the formula.
- Transmitter Power — use W.
- Antenna Gain — use dBd.
- Feed-Line Loss — use dB.
Output Guide
The results describe the calculated erp values for the inputs you entered. Check each value against the available space, selected components, feed system, and operating conditions before making a final design decision.
How This Calculator Works
The ERP uses ERP = PT × 10^((GdBd − L)/10), EIRP = ERP + 2.15 dB. Supply Transmitter Power (W), Antenna Gain (dBd), Feed-Line Loss (dB) in the displayed units, then use the calculated values as the first engineering target for this rf conversion design or analysis.
Design Notes
Effective Radiated Power (ERP) represents the effective transmitted power referenced to a half-wave dipole antenna after accounting for transmitter output, antenna gain, and feed-line losses. Increasing antenna gain improves ERP, while feed-line attenuation reduces the power delivered to the antenna. Accurate ERP calculations are essential when designing RF systems, estimating communication range, performing link budget analysis, and complying with national transmission power regulations. Since EIRP uses an isotropic radiator as its reference, it is always approximately 2.15 dB higher than ERP for the same antenna system. Practical performance may vary because of antenna efficiency, VSWR, impedance mismatch, connector losses, cable quality, environmental conditions, and installation accuracy.
Build and Tuning Notes
Use the calculated ERP and equivalent EIRP values when selecting antennas, transmitters, and feed-line components for an RF communication system. Verify antenna gain using manufacturer specifications or calibrated measurements, and minimise cable losses by selecting low-loss transmission lines and reducing unnecessary connectors. During installation, confirm transmitter output with RF power meters or spectrum analysers, maintain proper impedance matching, and ensure the final radiated power complies with local regulatory limits. Validate overall system performance through field testing or link budget verification before deployment.
Frequently Asked Questions
What is Effective Radiated Power (ERP)?
Effective Radiated Power (ERP) is the effective transmitted power of an antenna system referenced to a half-wave dipole antenna. It considers transmitter output power, antenna gain in dBd, and feed-line losses.
What is the difference between ERP and EIRP?
ERP uses a half-wave dipole as the reference antenna, while EIRP uses an ideal isotropic radiator. EIRP is always approximately 2.15 dB higher than ERP for the same transmitted signal.
How is ERP calculated?
ERP is calculated by combining transmitter power with antenna gain and subtracting feed-line losses. The resulting value represents the effective radiated power relative to a half-wave dipole antenna.
Why are feed-line losses important?
Feed-line losses reduce the amount of RF power reaching the antenna, lowering both ERP and communication range. Using shorter cable runs and low-loss coaxial cables helps improve overall system efficiency.
Where is an ERP Calculator commonly used?
ERP calculations are widely used in FM and television broadcasting, amateur radio, microwave links, wireless communication systems, cellular infrastructure, satellite communication, public safety radio networks, and RF engineering.
Why can measured ERP differ from calculated ERP?
Actual ERP may differ because of antenna efficiency, impedance mismatch, VSWR, connector losses, cable attenuation, manufacturing tolerances, environmental effects, and installation quality. Practical measurements and calibration help verify the final system performance.
Alex Warren
B.Sc. in Electrical & Electronic Engineering (EEE)
Alex specialises in antenna design and wave propagation. His expertise helps ensure these calculators present practical RF concepts, useful design estimates, and clear engineering guidance for students, HAM operators, and wireless professionals.