Calculadora de Atenuador RF
Atenuadores T, Pi, Bridged-T y de reflexión
Required Parameters
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Quick Answer
An RF attenuator reduces signal power by a precise dB amount while maintaining impedance matching. For a T-pad in 50 ohm: R_series = Z0 x (K-1)/(K+1), R_shunt = 2Z0K/(K^2-1), where K = 10^(dB/20).
Calculadora de Atenuador RF
Disene atenuadores resistivos T-pad, Pi-pad y Bridged-T para aplicaciones de RF y audio.
Atenuador T-Pad
Para impedancia Z0 y atenuacion A (dB):
- R1 = Z0 x (K - 1) / (K + 1) donde K = 10^(A/20)
- R2 = 2 x Z0 x K / (K^2 - 1)
Herramientas Relacionadas
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Design Notes
Resistive attenuators are frequency-independent in theory, but parasitic inductance and capacitance of physical resistors limit the usable frequency range. Through-hole pads work to about 100 MHz; SMD 0402 pads extend to 6 GHz. For broadband precision, use thin-film attenuator chips rated for your frequency range. Always verify return loss (>20 dB) and ensure each resistor can handle its share of the dissipated power.
Common Mistakes
- 1
Using a simple voltage divider instead of a matched-impedance pad — this causes reflections and VSWR problems.
- 2
Ignoring resistor power dissipation — at high attenuation, nearly all input power is dissipated as heat in the resistors.
- 3
Using wirewound resistors at RF frequencies — parasitic inductance destroys the flat frequency response above a few MHz.
Engineering Handbox
1. Calculate K = 10^(6/20) = 10^0.3 = 1.995\n2. R_series = 50 x (1.995-1)/(1.995+1) = 50 x 0.332 = 16.6 ohm\n3. R_shunt = 2 x 50 x 1.995 / (1.995^2 - 1) = 199.5 / 2.98 = 66.9 ohm
Knowledge Base
¿Para qué se usa un atenuador Pi?
Reduce la potencia de señal manteniendo la impedancia característica (50 o 75Ω) para evitar reflexiones.
¿Cómo elijo entre T y Pi?
T tiene menor capacitancia parásita (mejor para HF). Pi es más fácil en PCBs. Bajo 1 GHz, la diferencia es mínima.
¿Cuál es la fórmula del atenuador T?
R_serie = Z0 × (K-1)/(K+1), R_shunt = 2 × Z0 × K / (K²-1), donde K = 10^(dB/20).
¿Qué tolerancia de resistencia usar?
Laboratorio: 1% mínimo. Producción RF: 0.1% para atenuaciones superiores a 20 dB.
¿Cómo cascadeo atenuadores?
Sume los valores en dB. 3 dB + 6 dB = 9 dB total.
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