These SWR charts were generated using an Advantest R3767CG Vector Network Analyzer connected to the feed point at the base of the antenna. As each amateur band was swept, the vertical scale was adjusted to ‘center the plot’ and markers were set at each end and the center of the band.
For those who want to read the charts anyway, it’s very similar to an oscilloscope. The red line on the bottom represents an SWR of 1.0. Each division above the red line is an increase in SWR by the amount of the division, which is indicated in the upper right corner of the chart. (This would have been so simple if we hadn’t changed scale….)
10 Meter Band ->>
For the 10 Meter chart, the division is 200m or 0.2, so the first division above the red line would indicate an SWR of 1.2. For the 15 Meter chart the division is 500.0m or 0.5, so the first division above the red line would indicate an SWR of 1.5.
<<-15 Meter Band
17 Meter Band->>
<<-20 Meter Band
40 Meter Band->>
As the charts show, the ‘Curve of Goodness’, as a friend refers to SWR plots, is pretty darn good. Except for 15 Meters the SWR is below, in some cases well below, 1.5. Worst case on 15 Meters is 2.37, which can be corrected with an external tuner, and may be within the range of the built in tuners on many modern transceivers.
Hindsight being very accurate, it was a mistake to adjust the vertical scale. This makes the charts confusing at a glance; but the Marker List, below each chart, lists the frequency and SWR.
Thanks to Jim Cooper, AD7KT, for a job well done!