This calculator determines the two resistance values of a reflection attenuator. It is used in RF systems to achieve specific attenuation while maintaining matched impedance. This tool allows you to quickly design symmetrical controlled attenuation networks.
Useful for RF engineers, test technicians and circuit designers wanting to adjust signal level without disrupting system impedance matching.
Formulas
R1(Ω) < Zo = Zo × [ (10^(dB/20) - 1) / (10^(dB/20) + 1) ]
R1(Ω) > Zo = Zo × [ (10^(dB/20) + 1) / (10^(dB/20) – 1) ]
Explanation of formulas
- Zo is the characteristic impedance of the system, typically 50 Ω.
- dB represents the desired attenuation in decibels.
- The two resistors R1 < Zo and R1 > Zo create a symmetry allowing adaptation to be maintained while reducing the power of the reflected signal.
Calculation of a 10 dB reflection attenuator at 50 ohms
Input : Attenuation = 10 dB, Zo = 50 Ω
Exit :
- R1 < Zo = 21.2 Ω
- R1 > Zo = 118.1 Ω
Benefits and uses
- Ensures precise attenuation with perfect adaptation.
- Useful for calibration and power control in RF systems.
- Ideal for testing the linearity and performance of amplifiers.
- Practical tool for engineers and technicians working on microwave measurements.