Ratbastid: I don't know where you got that part... What about the telescope antennas that you find on radios and old TV sets? they can be put at any length the user wishes, doesn't change the frequency it receives...
you're thinking of the inherit frequency of a body I believe (absolutely sure that isn't the right word in english
)
by that I mean the frequency a body takes on when it's hit itself, like a string on a guitar... That has such properties, like fractions of the length etc.
Or I'm completely misunderstanding what you are saying to me, also a good possibility