We are not trying to be flippant with our answers, it is just that Return loss sometimes means very little.
If you have a pretty efficient antenna (i.e. one that is not electrically short, has low loss materials, etc), then return loss does mean more. If you have a poor antenna impedance match AND you have any length of line between the antenna and the receiver or transmitter, then you can have standing waves build up. As you then tune the frequency, you can have frequencies where the antenna works well, and at other frequencies the antenna will appear to work poorly.
For these relatively efficient antennas, like a quarterwave whip over a reasonably sized ground plane, it is really easy to tune its center frequency by simply snipping off small chunks of the whip's length while you watch the return loss on a network analyzer (always throw a few ferrite bead clamps on the line leading up to the antenna, to keep the coax line from becoming part of the tuning structure).