HP 85106D, Manual

Page: 76 / 244

HP 85106D mm-Wave System 2-31
Operation
Example Measurements
Figure 2-10 S
11
Shorted 10 cm Waveguide Section
With no delay applied, the reflection of the short is displayed at about
900 ps. Both the magnitude and location of this time domain response are
affected by the dispersive nature of the waveguide. The dispersion tends to
“smear” the trace making the peak magnitude value inaccurate. To obtain a
more exact measurement of the shorted line, add waveguide delay to move
the response to time, t=0. The delay required is 672 ps, or 201.65 mm which
is the twice the actual electrical length of the waveguide section. Twice
because the signal propagates from the port to the reflection and then back
to the port. Notice the change in magnitude due to the dispersion. The
corrected response now displays the actual effects of the loss in the line and
is unaffected by dispersion.