Choose your application Pick the job you are designing for. Each mode changes the quick-pick values and defaults, and shows extra panels: Metrology and Mil-Aero add Environmental Stability; Metrology and Quantum add a chain builder.
Rosenberger RF & Microwave Attenuation Calculator
Attenuator
Design resistive Pi and T pads for 50 Ω / 75 Ω RF and microwave systems. Enter a target attenuation and system impedance to get exact resistor values, standard-part rounding, VSWR, and power ratings — instantly.
dB
Insertion loss to introduce
Ω
50 Ω dominates RF/microwave; 75 Ω is common in broadcast & video coax. Source and load, matched.
W
For resistor power rating
Below about 1 dB, the resistor values become extreme (shunt resistors approach zero, or open) and this topology stops being practical. Consider a different attenuation or topology.
Pi Network
The schematic for the topology you chose, with each resistor labelled. It redraws as you switch between Pi and T.
Frequency limits: this is a lumped-element (DC-equivalent) model. Real pads roll off as lead/pad inductance and parasitic capacitance become significant relative to the resistor values — favor thin-film chip resistors, minimize trace length, and keep the layout symmetric for use above a few GHz.
Resistor Values
Exact series and shunt values for your attenuation and impedance, the nearest standard parts, and the match quality those parts give.
Voltage Ratio
3.162 : 1
Power Ratio
10.000 : 1
Output Power
100.0 mW
Match Quality (std. parts)
—
Power Budget
Each resistor’s dissipation against the rating you pick (50% derated): OK up to half the rating, Near limit up to the full rating, then Exceeds rating. In Quantum mode it checks fridge-stage cooling budgets instead.
Resistor power rating:
Ratings above assume continuous-wave (CW) dissipation at a 50% derating for reliability. For pulsed or high-PAR modulated signals, derate further from the peak envelope power, not the average.
Real-World Accuracy · Nearest 1% (E96) Parts
What you actually get if you build the pad with the nearest 1% (E96) resistors: achieved attenuation against your target, input VSWR and return loss.
Environmental Stability
Worst-case attenuation drift from resistor tolerance and temperature coefficient over the temperature range you choose. Shown in Metrology and Mil-Aero modes.— attenuation drift over temperature
to
± 0.00dB
Worst-case attenuation deviation from nominal, assuming both resistors drift by tolerance + TCR·ΔT from a 25°C reference, referenced to the nearest 1% standard values.
Attenuator Chain Builder
Split a large attenuation across cascaded pads. Totals add in dB, and each stage is checked against the power it receives (or its fridge stage in Quantum mode).
Total Attenuation
— dB
Final Output Power
—
Matched pads cascade additively in dB. Each stage below is checked against the Power Budget rating for its own incoming power — the earliest stages see the most power and are usually the constraint.