S11 measurements

A project log for HP 11947A clone

A refresh of the HP 11947A attenuator and limiter

james-wilsonJames Wilson 12/14/2019 at 00:490 Comments

One thing I forgot to characterize was the reflection measurements (S11 and S22). The 11947A datasheet cites a VSWR of < 1.7, and < 1.3 below 50 MHz for the input port. Setting up the board on the VNA, I measured S11:

The value at 200 MHz is 1.16. Well within spec, even beyond the operating range. Looking at the output port:

Also within the original spec of output port VSWR < 1.8, and < 1.2 below 50 MHz.