RF Attenuator Network Designer

Constant-impedance Pi and T attenuator calculator with real E-series resistor values, deviation, actual attenuation, impedance and power dissipation.

Network

Attenuation (dB)

System impedance (Ω)

Resistor series

Input power (W)

Schematic

Calculated resistor values

Resistor	Function	Ideal (Ω)	Selected	Deviation

Performance using selected resistor values

Actual attenuation
Insertion loss
Input impedance
Output impedance
Load power
Total resistor power
Power balance

Resistor power dissipation

Component	Power (W)	Percentage of input

Input power means real power entering the attenuator input port. The power calculation includes the actual input impedance and the selected resistor values.

Warnings

Formulas

K = 10^(A/20)
Pi: R1 = R3 = Z₀ (K + 1)/(K - 1)
Pi: R2 = Z₀ (K² - 1)/(2K)

K = 10^(A/20)
T: R1 = R3 = Z₀ (K - 1)/(K + 1)
T: R2 = 2 Z₀ K/(K² - 1)

Note: Calculated values assume equal source and load impedance and ideal lumped resistors. At very low or very high attenuation, parasitic resistance, inductance, capacitance and PCB layout can become important.