Analyze radiated power, accepted power, and resistance losses. Get efficiency, dB value, and waste estimates. Build better RF systems through clearer performance decisions daily.
Power Method: η = Pr / Pa
Resistance Method: η = Rr / (Rr + Rl)
Loss Power: Pl = Pa - Pr
Efficiency in dB: 10 × log10(η)
Estimated Gain: Gain(dBi) = Directivity(dBi) + 10 × log10(η)
Here, η is radiation efficiency, Pr is radiated power, Pa is accepted power, Rr is radiation resistance, and Rl is loss resistance.
| Case | Method | Inputs | Efficiency | Efficiency dB | Note |
|---|---|---|---|---|---|
| Example 1 | Power | Pr = 80 W, Pa = 100 W | 80% | -0.9691 dB | 20 W becomes loss. |
| Example 2 | Resistance | Rr = 48 Ω, Rl = 12 Ω | 80% | -0.9691 dB | Total resistance is 60 Ω. |
| Example 3 | Resistance | Rr = 36 Ω, Rl = 4 Ω, I = 2 A | 90% | -0.4576 dB | Pr = 144 W, Pa = 160 W. |
Radiation efficiency is a core antenna performance metric. It shows how much accepted input power becomes useful electromagnetic radiation. It also shows how much energy is lost inside conductors, dielectrics, loading parts, or nearby materials. Engineers use this value when comparing antennas, matching networks, and compact device layouts. A higher number usually supports better range, cleaner links, and lower wasted energy. A lower number often signals thermal loss, resistive loss, poor materials, or mechanical constraints that hurt performance.
Good efficiency helps an RF system deliver stronger field strength from the same input power. That can improve wireless coverage, sensor reliability, telemetry quality, and communication margin. Efficiency also affects gain. A highly directive antenna can still underperform if internal loss is too high. For that reason, engineers often review directivity and efficiency together. This calculator supports that workflow by estimating gain when optional directivity is entered. It gives a faster first-pass check during design reviews, lab analysis, or troubleshooting.
The power method uses radiated power divided by accepted power. This is helpful when test data or simulation results already report both values. The resistance method uses radiation resistance divided by total resistance. This is useful during antenna modeling and equivalent circuit analysis. If feed current is known, the calculator also estimates radiated power, loss power, and accepted power from resistance data. That provides a more complete engineering picture without needing another tool.
An efficiency near 100% means most accepted energy leaves the antenna as radiation. A moderate value means the design works but still wastes noticeable energy. A low value suggests that material loss, conductor loss, or compact packaging may be dominating performance. The dB view is useful because RF teams often compare gains and losses in logarithmic form. The loss percentage and loss factor also help explain how much performance is being sacrificed and where optimization effort may be justified.
Radiation efficiency is the ratio of useful radiated power to accepted input power. It tells you how much energy the antenna radiates instead of losing as heat or material loss.
The power method uses measured or simulated power values. The resistance method uses radiation resistance and loss resistance. Both methods describe the same physical efficiency from different input data.
dB format is common in RF work. It lets engineers compare gains and losses on the same logarithmic scale used for link budgets, antenna gain, and transmission loss.
No. A valid passive antenna cannot radiate more accepted power than it receives. Values above 100% usually indicate wrong measurements, wrong units, or incorrect input assumptions.
Common causes include thin conductors, lossy substrates, poor matching, nearby metal, tight packaging, small form factors, and dielectric loading from enclosures or surrounding structures.
No. Directivity describes how focused the radiation pattern is. Efficiency describes how much accepted power is actually radiated. Both combine to influence the final gain value.
Yes. If you know accepted power and radiated power, the power method is appropriate. Just keep units consistent and confirm that accepted power excludes reflected power.
Efficiency from resistance values does not require current. Current is only needed when you also want estimated radiated power, loss power, and accepted power in watts.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.