addition to a step attenuator a large fixed value attenuator
can be useful
for receiver sensitivity evaluations and amplifier gain evaluations
40dB fixed attenuator is derived from two 20dB Pi attenuation pads as shown in Fig 1 schematic below.
The use of two pads instead of just one 40dB pad was chosen as it can
be difficult to achieve a large dB step change due to r.f. leakage. The resistance values required were derived from paralleled on hand
resistors in stock. All
resistors are of a 5% tolerance however should be adequate for the
Attenuator schematic. The broken lines represent PCB pad shielding.
combinations to achieve required attenuation pad resistor values.
View of the assembly of the Standard Attenuator PCB ground for screen and component attachment.
2 View of the assembled
Front view of the assembled Standard Attenuator.
see step attenuator project: Sep
& Tee Network Resistive Attenuation Calculator
Pi-pad Attenuator - Equations
Pi and Tee Attenuators - Equations