4S6TMP.com — Pi and T attenuator with power dissipation
Pi attenuator: Two shunt resistors with a series resistor in between. Named for its resemblance to the Greek letter π. Good for matching higher impedances. The input and output shunt resistors connect to ground.
T attenuator: Two series resistors with a shunt resistor to ground in the middle. Good for matching lower impedances. More intuitive for some applications.
Minimum-loss pad: When input and output impedances are different, a minimum-loss pad provides the least possible attenuation while still matching. For 50Ω to 75Ω, the minimum loss is about 5.7 dB.