Calculator Inputs
Use equal mode for identical outputs. Use unequal mode when each branch needs a different power share.
Formula Used
1) Power unit conversion
dBm = 10 × log10(PmW)
2) Split fraction for each output
Fraction = Branch Ratio / Sum of Ratios
3) Ideal split loss per branch
Split Loss(dB) = -10 × log10(Fraction)
4) Ideal output power per branch
Pout,ideal(dBm) = Pin(dBm) + 10 × log10(Fraction)
5) Common loss estimate
Total Common Loss = Insertion Loss + Feed Loss + Safety Margin + Input Mismatch Loss + Output Mismatch Loss
6) Approximate mismatch loss from VSWR
Γ = (VSWR - 1) / (VSWR + 1)
Mismatch Loss(dB) = -10 × log10(1 - Γ²)
7) Actual branch output
Pout,actual(dBm) = Pout,ideal(dBm) - Total Common Loss
8) Voltage and current at each port
Vrms = √(P × Z)
Irms = √(P / Z)
9) Guided quarter-wave arm length
λg/4 = [c / (4 × f)] × Velocity Factor
How to Use This Calculator
- Choose the splitter topology you want to analyze.
- Enter input power and select W, mW, or dBm.
- Set the number of output ports.
- Select equal mode for identical branches.
- Select unequal mode and enter one ratio for each port.
- Enter system impedance, operating frequency, and velocity factor.
- Add insertion loss, feed loss, and design safety margin.
- Enter input and output VSWR values for mismatch estimates.
- Press the calculate button.
- Review the result cards, port table, and Plotly chart.
- Download the results as CSV or PDF when needed.
Example Data Table
| Case | Input Power | Ports | Mode | Loss Stack | Actual Output per Port | Total Delivered |
|---|---|---|---|---|---|---|
| Lab feeder split | 10 W | 4 | Equal | 0.98 dB | 1.995 W | 7.98 W |
| Unequal monitoring feed | 5 W | 3 | 50:30:20 | 0.85 dB | 2.06 W, 1.24 W, 0.82 W | 4.12 W |
| Low power test rack | 30 dBm | 2 | Equal | 0.55 dB | 4.41 dBm equivalent W values | 8.81 W |
These rows show typical engineering scenarios for checking balance, losses, and delivered power before hardware selection.
FAQs
1) What is the difference between split loss and insertion loss?
Split loss is the theoretical power division caused by sharing input power across branches. Insertion loss is additional real-world loss from conductors, dielectric effects, connectors, and construction imperfections.
2) When should I use unequal split mode?
Use unequal mode when one branch must carry more power than another. It is useful for monitoring ports, cascaded feeds, directional test paths, or intentionally unbalanced network distribution.
3) Why do VSWR values matter here?
VSWR represents mismatch between transmission lines and terminations. Poor matching reflects part of the signal, reduces delivered power, and raises uncertainty in actual branch output estimates.
4) Can this calculator help with Wilkinson design work?
Yes. It estimates quarter-wave arm length from frequency and velocity factor. For equal Wilkinson cases, it also shows the typical branch line impedance estimate used during first-pass layout work.
5) Does isolation change the output power directly?
Isolation mainly describes how well one output port is separated from another. It affects port interaction and stability more than direct forward power, so it is shown as a design reference value.
6) Which power unit is best for RF design?
dBm is often easiest for cascaded RF calculations because gains and losses add directly in decibels. Watts are more intuitive for total delivered energy and thermal handling checks.
7) Why is total delivered power lower than input power?
A practical splitter always loses some power through insertion loss, mismatch, feed attenuation, and intentional design margin. The calculator combines these effects into a common loss estimate.
8) Can a splitter also work as a combiner?
Many passive splitter structures can operate in reverse as combiners. Actual combining performance still depends on phase alignment, amplitude balance, isolation, and matching conditions.
Save this file as rf_power_splitter.php.