VNA setup
Points for linear and segmented frequency sweeps, boundary checks for gaps and step jumps, and power-sweep sizing.
One segment is a plain linear sweep. Every frequency carries its own unit, so a kilohertz step sits beside a gigahertz stop. Points include both ends, so 100 MHz to 125 GHz in 10 MHz steps is 12 491 points.
Points at 1, 1+k, 1+2k … times each decade, one linear segment per decade, so every frequency is a round number. Add a linear tail where the DUT lives. Generating replaces the segment rows below.
| # | Start | Stop | Step | Points | Last point | Δf/f start → stop | Avg points / decade | Points / decade start → stop |
|---|
Contiguous means the next segment starts within one step of the previous last point. A log-style decade table repeats its pattern, so comparing the relative step Δf/f at adjacent segment starts is smooth (ratio 1×) even though the absolute step jumps 10×. Choose the absolute comparison for tables meant to be linear throughout. A linear tail that is denser than the decades is reported through its points per decade, not as a boundary fault.
| At | Transition | Step ratio | Δf/f-at-start ratio | Check |
|---|
Enter step or points; the other updates. Points include both ends: −20 dBm to −4 dBm in 0.1 dB steps is 161 points.
N = (stop − start)/step + 1 for a linear segment. Relative spacing Δf/f sets how well narrow features are resolved; points per decade is 1/log₁₀(1 + Δf/f). A log sweep with the same span needs ⌈ln(flast/ffirst)/ln(1 + r)⌉ + 1 points for relative spacing r. Minimum sweep time is about N/IFBW before band crossings, settling, and dwell.
Segment count, total points, and per-segment IF bandwidth or power are instrument settings; check the analyzer's limits.
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