Hi,

I tried a shortwave radio group first, but no answers.
Should have posted here, first.

Enjoy sw listening, but frankly not all that sharp re antennas.

Over the past few months, I have seen several ads for those handheld sw
receivers and transceivers. From different mfgs.
About the size of the typical hand-held scanner receiver.

They all seem to cover up to at least 30 MHz, and most beyond.

Got to thinking about this a bit.
What do they use for an antenna for 30 MHz and below ?

I have a long end fed antenna for my listening.
Obviously they have a short "something" antenna.

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

How can it work down there at all ?

I can visualize s tuned ferrite loop, such as the very old fashioned AM
table radios used to have, but wouldn't this only be effective over a
very small range ?

Or, do they expect you to hook up something "decent" to it, even though
it is supposed to be portable, and is very small ?

Any technical explanation on this would be most appreciated.

Thanks,
Bob

On Sat, 03 Jul 2010 14:52:15 -0400, Bob wrote:

I have a long end fed antenna for my listening.
Obviously they have a short "something" antenna.

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

How can it work down there at all ?

I can visualize s tuned ferrite loop, such as the very old fashioned AM
table radios used to have, but wouldn't this only be effective over a
very small range ?

Hi Bob,

A make and model number would get you a more definitive answer.
However, for the broader question, and as you undoubtedly expect, more
antenna is better - to a point. Some will argue, theoretically,
otherwise. I go with results.

When I was in South Africa (no, not the World Cup), I took along one
of Radio Shack's cheapest SW radios. It had the conventional whip,
and it offered the conventional whimp. However, having foresight, I
also took along about 20 feet of wirewrap wire with a quarter taped
onto one end. At the close of day, I would wrap one end around the
shortened whip and I would toss the quarter into the rafters (we
stayed in thatched covered huts), all of a ten or fourteen foot
height; and signals came booming in from all over the continent and
Europe.

Another thing missing from these small jobs are a tuned front end. In
fact, you can spend a lot of money on SW radios and still not get
front end tuning. A preselector, or simple antenna tuner (as cheap as
one as you can find, or build one for $10) will go far, far, far.

73's
Richard Clark, KB7QHC

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