This attenuator is a 1/ 2/ 3/ 5/ 10/ 20/ 20/ 20 dB model and is built
as a microstrip circuit using regular 1.6mm thick epoxy PCB.
It is a standard Pi attenuator which
attenuation range is about 0 - 70 dB and accuracy better than
+/-0.5 dB. Its -3dB frequency response is around 400 MHz
All components (DPDT switches, BNC connectors and SMD 1206 0.25W resistors are soldered on the track side of the PCB, the other side being the ground plane. In order to obtain good frequency response it is recommended to cut the switches pins as short as possible.The SMD resistors will be paralleled (one on top of the other) if necessary (click here for inside picture of the attenuator) .
A small compensation capacitor may be connected at the input and
output to improve the Return Loss. On my attenuator, the Return Loss
is better than -25 dB for frequencies lower than 400 MHz.
