In article ,
Bob wrote:

How effective is a short "something" around 5 to 10 MHz, e.g. ?

How can it work down there at all ?

Bob-

Like Richard, I have one of the small Radio Shack SW Receivers. I think
it was made for them by Sangean. It has a telescoping antenna that may
be as long as 36 inches when extended. No, a 36 inch antenna is not as
good as a longer wire for Shortwave reception.

Someone with a better understanding of antenna theory may be able to
calculate just how much worse it is, but suppose it receives a signal at
a 20 dB lower level (1/100th the power level or 1/10th the voltage) than
a full-size antenna. All you need is a stronger signal to make up for
it. But when propagation is good, signals can be quite strong.

Even so, it wouldn't hurt to take along some extra antenna wire!

Fred