Thanks for the response Howard. For my purposes, it is fine but I expected the 'best' point to be defined by the 50 ohm terminator and was surprised to see over 5 dB more return loss at the resonant point of the antenna. It feels like there is something else going on that I don't have an understanding of... Accuracy of the RLB should not be a factor becaus this is a relative measurement between the 50 ohm terminator and the antenna - right? The terminator measures 50.06 ohms on my BM 869 meter so I think that would not be off enough to matter. I swapped cables, but the results were the same. Could there be some other reactance happening that could cause this? In other words, since this is a SA and not a VNA (and therefore I don't see the reactance vector), if I am not at 50 - j0 but some other reactive value, could it show a higher return loss than the 50 ohm resistive load? (RF does mystify me sometimes...)
Hi Hammy, I normalized, then put the 50 ohm terminator on to get the purple trace, and then the antenna to get the yellow trace. I get the same results when I use the VSWR function. For this screen shot, it was easier to just show the return loss directly insteadof invoking the VSWR function.
Len