So, recently, I've thought to get more serious about trying to use an
RTL-SDR type computer dongle, to try and recieve SW broadcasts (and
anything else, as opportunity allows). What I'd like to ask is this.

Included with the dongle is a magnetic mounted antenna system, that
I'll mount on a backing pan, as well as a 1.5 meter,and (I think) a
1.0 meter telescoping antenna. Is there anything I can do, in terms of
perhaps tweaking how far I telescope the main element out, to tune it
to a particular band?

Or am I just SOL, and should upgrade to a better antenna, without
exception?