Mismatch loss related
to SWR

The graph sheet is a tool that is used to see which guiding dB mismatch loss is obtained if the SWR of the antenna is above 1.

Here please notice that it is not always maximum gain at minimum SWR.

Example:
With the above in mind and on the basis of the graph - an antenna having an SWR of 1.5 will have a 0.25 dB loss proportional to an antenna with an SWR of 1.0. However, antennas will seldomly have an SWR of 1 in a rather large frequency range.

Large drawing: Mismatch Loss related to SWR

An antenna that has an SWR of 2 at the band edges will have a loss of approx. 0.6 dB compared to an antenna with an SWR of 1. If you assume that the loss is seen in relation to an SWR of 1.5 the loss will then be:
0.6 - 0.25 = 0.35 dB which is negligible.